Programming Interface Information: This information is NOT intended to be used as Programming Interfaces of z/VM.

#### MCKBK

Prolog

Control Block Contents
MCKBK DSECT

Storage Layout

Cross Reference (Contains links to field and bit definitions)

#### MCKBK Prolog

     NAME       : HCPMCKBK
     DESCRIPTION: MACHINE CHECK DESCRIPTOR BLOCK
     DSECT      : MCKBK
     FUNCTION   : THE MCKBK IS THE MAIN WORK AREA OF THE MACHINE-CHECK AND
                  CHECK-STOP HANDLERS.  THE FIRST PART CONTAINS 'FOOTPRINT'
                  FLAGS, AND A LOCAL TRACE TABLE FOR MACHINE CHECKS, AND
                  OTHER STATUS FIELDS THAT MIGHT BE USEFUL IN DEBUGGING.
                  THIS FIRST PART OF THE MCKBK IS APPENDED TO (AND RECORDED
                  WITH) THE ERROR RECORD AND IS OCCASIONALLY REFERRED TO AS
                  THE 'DAMAGE ASSESSMENT AREA'.  THE SECOND PART OF THE MCKBK
                  IS NOT REGARDED AS VALUABLE FOR DEBUGGING AND CONSEQUENTLY
                  IS NOT INCLUDED IN THE RECORDED ERROR RECORD.  THIS PART
                  OF THE MCKBK IS SOMETIMES REFERRED TO AS THE 'MACHINE-CHECK
                  WORK AREA'.
                  DATA IS PLACED IN THE MCKBK AT THE START OF AN ERROR
                  INCIDENT (MACHINE CHECK OR CHECK-STOP) AND, FOR THE MOST
                  PART, IS NOT CLEARED UNTIL THE START OF THE NEXT INCIDENT.
     LOCATED BY : A CPU'S MCKBK IS ANCHORED IN THE CPU'S PREFIX PAGE,
                  POINTED TO BY PFXMCHA.
     CREATED BY : HCPMPS    WHEN A PROCESSOR IS INITIALIZED.  EACH CPU HAS
                  ONE OF THESE BLOCKS, ALLOCATED AT SYSTEM
                  INITIALIZATION TIME OR WHEN THE CPU IS VARIED
                  ONLINE.
                  NOTES      : TO ACCOMODATE APPENDING THE MCKBK TO THE
                  ERROR RECORD (MCHREC), THE MCHREC AND THE MCKBK
                  ARE ALLOCATED FROM A SINGLE BLOCK OF STORAGE.
     DELETED BY : HCPMPS    TWO MINUTES AFTER A PROCESSOR IS VARIED OFFLINE.

#### MCKBK Control Block Content

#### MCKBK DSECT

    Hex   Dec Type/Val   Lng Label (dup)    Comments
    ---- ---- --------- ---- -------------- --------
    0000    0 Structure      MCKBK          MACHINE CHECK DESCRIPTOR BLOCK
    0000    0 Dbl-Word     8 MCKDAMAG (0)   START OF DAMAGE ASSESSMENT AREA.
    0000    0 Signed       2 MCKCNT2N       COUNT OF SECONDARY MACHINE CHECKS
                                            SUBSEQUENT TO MOST RECENT
                                            PRIMARY.
    0002    2 Signed       2 MCKCNTEQ       COUNT OF CONSECUTIVE IDENTICAL
                                            MACHINE CHECKS (MCIC'S). WHEN
                                            THIS COUNT EXCEEDS A THRESHOLD
                                            (MCKTHLD1), ERROR RECORDING IS
                                            SUSPENDED (RECORDS ARE DISCARDED)
                                            UNTIL THE COUNT IS RESET. THE
                                            COUNT IS RESET WHEN A DIFFERENT
                                            MACHINE CHECK OCCURS. BUT EVEN
                                            WHEN THIS COUNT IS NOT SET, AN
                                            ERROR IS ALLOWED TO BE RECORDED
                                            ROUGHLY EVERY (MCKTIM1) SECONDS.
              00000009       MCKTHLD1       9 THRESHOLD ASSOCIATED WITH
                                            MCKCNTEQ.
              00000258       MCKTIM1        600 UNIT IS SECONDS, APPROX. (SEE
                                            MCKCNTEQ).
    0004    4 Signed       2 MCKCNT         COUNT OF RECENT MACHINE CHECKS.
                                            WHEN THIS COUNT EXCEEDS A
                                            THRESHOLD (MCKTHLD2), ERROR
                                            RECORDING IS SUSPENDED (RECORDS
                                            ARE DISCARDED) UNTIL THE COUNT IS
                                            RESET. THE COUNT IS RESET WHEN A
                                            MACHINE CHECK OCCURS AND AT LEAST
                                            (MCKTIM2) SECONDS HAVE ELAPSED
                                            SINCE THE LAST RESET.
              0000000A       MCKTHLD2       10 THRESHOLD ASSOCIATED WITH
                                            MCKCNT.
              0000012C       MCKTIM2        300 UNIT IS SECONDS, APPROX. (SEE
                                            MCKCNT).
    0006    6 Signed       2 MCKHOTMK       MASK OF RECENT ERROR CONDITIONS,
                                            THE 'OR' OF RECENT MACHINE CHECKS
                                            (MCIC BITS 0-15).
    0008    8 Dbl-Word     8 MCKFLAGS (0)   ENCOMPASSES THE FOLLOWING 8 FLAG
                                            BYTES. THIS LABEL IS USED TO
                                            RESET ALL 8 AS A GROUP.
    0008    8 Bitstring    1 MCKFMISC       MISCELLANEOUS STATUS FLAGS.
              1... ....      MCKFIXUP       X'80' SOME PROGRESS WAS MADE
                                            TOWARD RECOVERY. (AT LEAST ONE
                                            ERROR WAS CORRECTED.) THIS FLAG
                                            IS NOT A MERE FOOTPRINT; IT MUST
                                            BE MAINTAINED VERY PRECISELY AND
                                            MUST NOT BE TURNED ON CASUALLY.
                                            IT MUST BE TURNED ON ONLY WHEN A
                                            PROBLEM HAS REALLY BEEN FIXED,
                                            OTHERWISE, IN THE CASE OF
                                            'PROCESSING BACKUP' WE MAY END
                                            RETRYING A HOPELESS CASE
                                            ENDLESSLY.
              .1.. ....      MCKFSIE        X'40' WE WERE RUNNING SIE
                                            (PFXHSIE WAS SET).
              ..1. ....      MCKFHOT        X'20' INTERRUPT CLASSIFIED HOT.
                                            NOT REPORTED.
    0009    9 Bitstring    1 *              RESERVED FOR FUTURE IBM USE.
    000A   10 Bitstring    1 MCKFETYP       TYPE OF ERROR.
              .1.. ....      MCKFERCS       X'40' ERROR WAS CHECK-STOP, NOT
                                            MACHINE CHECK.
              ..1. ....      MCKF2ND        X'20' A SECONDARY ERROR OCCURRED
                                            WHILE HANDLING A MACHINE CHECK.
              ...1 ....      MCKF2CS        X'10' SECONDARY ERROR WAS A
                                            CHECK-STOP.
              .... 1...      MCKFMCIC       X'08' INVALID MCIC (REQUIRED BITS
                                            MISSING).
              .... .1..      MCKFABND       X'04' POSSIBLE SOFTWARE ERROR
                                            ENCOUNTERED. WHERE WE CANNOT
                                            ISSUE HCPABEND, WE SET THIS FLAG,
                                            THEN TERMINATE.
    000B   11 Bitstring    1 MCKFTERM       SYSTEM TERMINATION STATUS.
              1... ....      MCKFEMER       X'80' EMERGENCY HOST TERMINATION
                                            REQUIRED (AND OTHER FLAGS MAY BE
                                            MEANINGLESS).
              .1.. ....      MCKFNOTM       X'40' HOST TERMINATION NOT
                                            REQUIRED BY THE MACHINE-CHECK
                                            FLIH.
              ..1. ....      MCKFDIE1       X'20' HOST TERMINATION WAS
                                            REQUIRED BY THE MACHINE-CHECK
                                            FLIH.
              ...1 ....      MCKFDIE2       X'10' HOST TERMINATION WAS
                                            REQUIRED BY THE MACHINE-CHECK
                                            SLIH.
              .... 1...      MCKFIPL        X'08' SOFT-RE-IPL AFTER TERMINATE
                                            DISALLOWED.
              .... .1..      MCKFIPLI       X'04' SOFT-RE-IPL DISALLOWED BY
                                            IO SUB-SYSTEM.
    000C   12 Bitstring    1 *              RESERVED FOR FUTURE IBM USE.
    000D   13 Bitstring    1 MCKFOOT5       FOOTPRINTS: MISCELLANEOUS.
              1... ....      MCKFVFIX       X'80' VIRTUAL SIDE WAS TOLD
                                            DAMAGE WAS FIXED.
              .1.. ....      MCKFZTOD       X'40' FOUND TOD CLOCK BROKEN.
                                            TIMESTAMP IN MCHTOD AND IN TRACE
                                            ENTRY IS ALL FF'S.
    000E   14 Bitstring    1 MCKFOOT6       FOOTPRINTS: CORRECTIVE ACTIONS
                                            TAKEN.
              1... ....      MCKFXCTL       X'80' RE-ESTABLISHED HOST CONTROL
                                            REGISTERS.
              ..1. ....      MCKFXCKC       X'20' RE-ESTABLISHED CLOCK
                                            COMP'TOR (APPROX).
              ...1 ....      MCKFXPT        X'10' RE-ESTABLISHED CPU TIMER
                                            (APPROX).
              .... 1...      MCKFXTPR       X'08' Re-established TOD
                                            Programmable Register
    000F   15 Bitstring    1 MCKFOOT7       FOOTPRINTS: CORRECTIVE ACTIONS
                                            TAKEN.
              1... ....      MCKFATSK       X'80' ATTEMPTED TO RUN
                                            INTERRUPTED SYSTEM TASK TO
                                            COMPLETION.
              .1.. ....      MCKFXTSK       X'40' ATTEMPT TO COMPLETE
                                            INTERRUPTED SYSTEM TASK WAS
                                            SUCCESSFUL.
              ..1. ....      MCKFRMOF       X'20' MARKED FRAME TO BE TAKEN
                                            OFFLINE.
              ...1 ....      MCKFXKEY       X'10' RESTORED HOST STORAGE KEY.
              .... 1...      MCKFXPAG       X'08' ACTED TO REFRESH AN
                                            UNCHANGED GUEST PG.
    0010   16 Dbl-Word     8 * (0)
    0010   16 Bitstring   16 MCKCLKS (0)    LABEL FOR MOVING BOTH CLOCKS AT
                                            ONCE.
    0010   16 Dbl-Word     8 MCKCTIMR       LOGGED OUT CPU TIMER.
    0018   24 Dbl-Word     8 MCKCCOMP       LOGGED OUT CLOCK COMPARATOR.
    0020   32 Dbl-Word     8 MCKTRC (0)     START OF LOCAL TRACE TABLE. THE
                                            ENTRIES IN THIS TABLE ARE DEFINED
                                            BY A REDEFINITION (ORG) OF
                                            MCKTRCUR (BELOW).
    0020   32 Bitstring   16 MCKTRC1        OLDEST ENTRY IN TRACE TABLE.
    0030   48 Bitstring   16 MCKTRC2        2ND OLDEST ENTRY IN TRACE TABLE.
    0040   64 Bitstring   16 MCKTRC3        ETC.
    0050   80 Bitstring   16 MCKTRC4        ETC.
    0060   96 Bitstring   16 MCKTRCUR       CURRENT (MOST RECENT) TRACE
                                            ENTRY.
              00000070       MCKTRCZ        * MARKS END OF TRACE TABLE.
    0070  112 Signed       4 *              RESERVED FOR FUTURE IBM USE.
    0074  116 Signed       2 *              RESERVED FOR FUTURE IBM USE.
    0076  118 Signed       2 MCKCPUAD       'STAP' CPUID, FOR MSG'S ISSUED BY
                                            SLIH.
              00000078       MCKDLEN        *-MCKBK LENGTH OF DAMAGE
                                            ASSESSMENT AREA.
              0000000F       MCKDSIZE       (MCKDLEN+7)/8 SIZE (DBLWDS) OF
                                            D.A. AREA.
            END OF DAMAGE ASSESSMENT AREA.  THE ABOVE PORTION OF THE
            MCKBK IS APPENDED TO THE RECORDED MACHINE CHECK ERROR RECORD.
            START OF MACHINE CHECK WORK AREA.  THE FOLLOWING PORTION OF THE
            MCKBK IS STRICTLY A WORK AREA AND IS NOT INCLUDED IN ERROR RECORD.
    0078  120 Signed       4 MCKREC         ADDRESS OF RECORDING RECORD
                                            (MCHREC).
    007C  124 Bitstring    1 MCKFAILF       FAILURE CLASSIFICATION CONTROL
                                            FLAGS
              1... ....      MCKSOMIN       X'80' SOME HOST VALIDITY BITS ARE
                                            INVALID
              .1.. ....      MCKFORCE       X'40' This failure must be forced
                                            to hard
              ...1 ....      MCKHARD        X'10' HARD FAILURE WAS
                                            ENCOUNTERED
              .... 1...      MCKDEGRP       X'08' DEGRADE FAILURE TO PASS TO
                                            GUEST
              .... .1..      MCKDEGRN       X'04' DEGRADE FAILURE NOT TO PASS
                                            TO GUEST
              .... ..1.      MCKPASS        X'02' FAILURE TO BE PASSED TO
                                            GUEST
              .... ...1      MCKSOFT        X'01' SOFT FAILURE WAS
                                            ENCOUNTERED
    007D  125 Bitstring    1 MCKRECFL       Machine Check Recording Checks
                                            Flags
              1... ....      MCKCPREC       X'80' CP will record this error
                                            check record
              .1.. ....      MCKLFREC       X'40' The machine check handler
                                            is looking for a virtual machine
                                            to record the machine check
                                            record .
    007E  126 Bitstring    1 MCKIACR        Saved PFXIACR
    007F  127 Bitstring    1 MCKIACE        Saved PFXIACE
    0080  128 Signed       4 MCKHNDL2       ADDRESS POINTING TO A SECONDARY
                                            MACHINE CHECK HANDLER, OR ZERO IF
                                            THE PRIMARY HANDLER IS TO HANDLE
                                            THE MACHINE CHECK.
    0084  132 Signed       4 MCKC14SV       VALUE IN CR14 PRIOR TO MACHINE
                                            CHECK.
    0088  136 Signed       4 MCKTODR2       1ST 4 BYTES OF TOD AT LAST MCKCNT
                                            RESET.
    008C  140 Signed       4 MCKTODR1       1ST 4 OF TOD AT LAST MCKCNTEQ
                                            OVERRIDE.
    0090  144 Bitstring    1 MCKCLEAR (0)   WE ZERO ALL FIELDS BETWEEN HERE
                                            AND MCKEND (AND A FEW OF THE
                                            PRECEEDING FIELDS AS WELL) WHEN
                                            WE START PROCESSING A PRIMARY
                                            MACHINE CHECK.
    0090  144 Dbl-Word     8 MCKHIC (0)     WORKING MCIC FOR HOST. THIS
                                            STARTS OUT AS A COPY OF THE REAL
                                            MCIC, THEN WE ALTER THE VALIDITY
                                            BITS IN IT AS WE CORRECT DAMAGE
                                            OR DISCOVER MORE DAMAGE. IT'S
                                            VALIDITY BITS MAINTAIN A RUNNING
                                            SCORE, AS WE GO THRU THE
                                            MACHINE-CHECK HANDLER, OF WHAT
                                            ENTITIES REMAIN DAMAGED.
    0090  144 Bitstring    1 MCKHIC0        HOST WORKING COPY, MCIC BYTE 0.
              1111 1111      MCIPRIM0       X'FF' PRIMARY MACHINE CHECK BITS
                                            - BYTE 0
              1... ....      MCICSD         X'80' SYSTEM DAMAGE BIT.
              .1.. ....      MCICPD         X'40' PROCESSING DAMAGE BIT.
              ..1. ....      MCICSR         X'20' SYSTEM RECOVERY BIT.
              ...1 ....      MCICITD        X'10' INTERVAL TIMER DAMAGE. (370
                                            GUESTS)
              .... 1...      MCICCD         X'08' TIMING (CLOCK) FACILITY
                                            DAMAGE.
              .... .1..      MCICED         X'04' EXTERNAL DAMAGE.
              .... ...1      MCICDG         X'01' DEGRADATION BIT.
    0091  145 Bitstring    1 MCKHIC1        HOST WORKING COPY, MCIC BYTE 1.
              1111 ....      MCIPRIM1       X'F0' PRIMARY MACHINE CHECK BITS
                                            - BYTE 1
              1... ....      MCICW          X'80' WARNING BIT.
              .1.. ....      MCICCRW        X'40' PENDING-CRW REPORT.
              ..1. ....      MCICSP         X'20' SERVICE PROCESSOR DAMAGE.
              ...1 ....      MCICCSD        X'10' CHANNEL-SUBSYSTEM DAMAGE.
              .... ..1.      MCICBU         X'02' 'BACKED UP' BIT.
              .... ...1      MCICDL         X'01' 'DELAYED' BIT. (370 GUESTS)
    0092  146 Bitstring    1 MCKHIC2        HOST WORKING COPY, MCIC BYTE 2.
              1... ....      MCICSE         X'80' STORAGE ERROR UNCORRECTED.
              .1.. ....      MCICSC         X'40' STORAGE ERROR CORRECTED.
              ..1. ....      MCICKE         X'20' STORAGE-KEY ERROR
                                            UNCORRECTED.
              ...1 ....      MCICSDG        X'10' STORAGE DEGRADATION.
                                            MODIFIES STORAGE ERROR CORRECTED.
              .... 1...      MCICVWP        X'08' BITS 12-15 OF MC OLD PSW
                                            VALID.
              .... .1..      MCICVMS        X'04' SYSTEM MASK & KEY OF MC OLD
                                            PSW VALID.
              .... ..1.      MCICVPM        X'02' PROGRAM MASK & CC OF MC OLD
                                            PSW VALID.
              .... ...1      MCICVIA        X'01' INSTR ADDR OF MC OLD PSW IS
                                            VALID.
    0093  147 Bitstring    1 MCKHIC3        HOST WORKING COPY, MCIC BYTE 3.
              1... ....      MCICVFA        X'80' FAILING STORAGE ADDRESS IS
                                            VALID.
              ..1. ....      MCICVED        X'20' EXTERNAL-DAMAGE CODE IS
                                            VALID.
              ...1 ....      MCICVFP        X'10' FP REGISTERS STORED ARE
                                            VALID.
              .... 1...      MCICVGR        X'08' GP REGISTERS STORED ARE
                                            VALID.
              .... .1..      MCICVCR        X'04' CONTROL REGISTERS STORED
                                            VALID.
              .... ..1.      MCICVLG        X'02' EXTENDED LOGOUT AREA IS
                                            VALID.
              .... ...1      MCICVST        X'01' INST. MODIFIED STORAGE IS
                                            VALID.
    0094  148 Bitstring    1 MCKHIC4        HOST WORKING COPY, MCIC BYTE 4.
    0095  149 Bitstring    1 MCKHIC5        HOST WORKING COPY, MCIC BYTE 5.
              ..1. ....      MCICVTPR       X'20' TOD programmable register
                                            validity
              ...1 ....      MCICVXFP       X'10' Additional FP Registers
                                            Validity (ESA390) FP Control
                                            Register Validity (zArch)
              .... 1...      MCICAR         X'08' Ancillary Report Bit
              .... ..1.      MCICVCT        X'02' CPU TIMER STORED IS VALID.
              .... ...1      MCICVCC        X'01' CLOCK COMPARATOR STORED IS
                                            VALID.
    0096  150 Signed       2 MCKHIC6        HOST WORKING COPY, MCIC BYTES 6 &
                                            7.
    0098  152 Dbl-Word     8 MCKGIC (0)     WORKING MCIC FOR GUEST. THIS
                                            STARTS OUT AS A COPY OF THE REAL
                                            MCIC, THEN WE ALTER THE VALIDITY
                                            BITS IN IT AS WE CORRECT DAMAGE
                                            OR DISCOVER MORE DAMAGE. IT'S
                                            VALIDITY BITS MAINTAIN A RUNNING
                                            SCORE, AS WE GO THRU THE
                                            MACHINE-CHECK HANDLER, OF WHAT
                                            ENTITIES REMAIN DAMAGED.
    0098  152 Bitstring    1 MCKGIC0        GUEST WORKING COPY, MCIC BYTE 0.
              1111 1111      MCIPRIM0       X'FF' PRIMARY MACHINE CHECK BITS
                                            - BYTE 0
              1... ....      MCICSD         X'80' SYSTEM DAMAGE BIT.
              .1.. ....      MCICPD         X'40' PROCESSING DAMAGE BIT.
              ..1. ....      MCICSR         X'20' SYSTEM RECOVERY BIT.
              ...1 ....      MCICITD        X'10' INTERVAL TIMER DAMAGE. (370
                                            GUESTS)
              .... 1...      MCICCD         X'08' TIMING (CLOCK) FACILITY
                                            DAMAGE.
              .... .1..      MCICED         X'04' EXTERNAL DAMAGE.
              .... ...1      MCICDG         X'01' DEGRADATION BIT.
    0099  153 Bitstring    1 MCKGIC1        GUEST WORKING COPY, MCIC BYTE 1.
              1111 ....      MCIPRIM1       X'F0' PRIMARY MACHINE CHECK BITS
                                            - BYTE 1
              1... ....      MCICW          X'80' WARNING BIT.
              .1.. ....      MCICCRW        X'40' PENDING-CRW REPORT.
              ..1. ....      MCICSP         X'20' SERVICE PROCESSOR DAMAGE.
              ...1 ....      MCICCSD        X'10' CHANNEL-SUBSYSTEM DAMAGE.
              .... ..1.      MCICBU         X'02' 'BACKED UP' BIT.
              .... ...1      MCICDL         X'01' 'DELAYED' BIT. (370 GUESTS)
    009A  154 Bitstring    1 MCKGIC2        GUEST WORKING COPY, MCIC BYTE 2.
              1... ....      MCICSE         X'80' STORAGE ERROR UNCORRECTED.
              .1.. ....      MCICSC         X'40' STORAGE ERROR CORRECTED.
              ..1. ....      MCICKE         X'20' STORAGE-KEY ERROR
                                            UNCORRECTED.
              ...1 ....      MCICSDG        X'10' STORAGE DEGRADATION.
                                            MODIFIES STORAGE ERROR CORRECTED.
              .... 1...      MCICVWP        X'08' BITS 12-15 OF MC OLD PSW
                                            VALID.
              .... .1..      MCICVMS        X'04' SYSTEM MASK & KEY OF MC OLD
                                            PSW VALID.
              .... ..1.      MCICVPM        X'02' PROGRAM MASK & CC OF MC OLD
                                            PSW VALID.
              .... ...1      MCICVIA        X'01' INSTR ADDR OF MC OLD PSW IS
                                            VALID.
    009B  155 Bitstring    1 MCKGIC3        GUEST WORKING COPY, MCIC BYTE 3.
              1... ....      MCICVFA        X'80' FAILING STORAGE ADDRESS IS
                                            VALID.
              ..1. ....      MCICVED        X'20' EXTERNAL-DAMAGE CODE IS
                                            VALID.
              ...1 ....      MCICVFP        X'10' FP REGISTERS STORED ARE
                                            VALID.
              .... 1...      MCICVGR        X'08' GP REGISTERS STORED ARE
                                            VALID.
              .... .1..      MCICVCR        X'04' CONTROL REGISTERS STORED
                                            VALID.
              .... ..1.      MCICVLG        X'02' EXTENDED LOGOUT AREA IS
                                            VALID.
              .... ...1      MCICVST        X'01' INST. MODIFIED STORAGE IS
                                            VALID.
    009C  156 Bitstring    1 MCKGIC4        GUEST WORKING COPY, MCIC BYTE 4.
    009D  157 Bitstring    1 MCKGIC5        GUEST WORKING COPY, MCIC BYTE 5.
              ..1. ....      MCICVTPR       X'20' TOD programmable register
                                            validity
              ...1 ....      MCICVXFP       X'10' Additional FP Registers
                                            Validity (ESA390) FP Control
                                            Register Validity (zArch)
              .... 1...      MCICAR         X'08' Ancillary Report Bit
              .... ..1.      MCICVCT        X'02' CPU TIMER STORED IS VALID.
              .... ...1      MCICVCC        X'01' CLOCK COMPARATOR STORED IS
                                            VALID.
    009E  158 Signed       2 MCKGIC6        GUEST WORKING COPY, MCIC BYTES 6
                                            & 7.
    00A0  160 Signed       4 MCKHXDC (0)    Host external damage code
    00A0  160 Bitstring    1 MCKHXDC0       Byte 0 of the external damage
                                            code
              .... ....      MCEXTD0        X'00' No bits defined
    00A1  161 Bitstring    1 MCKHXDC1       Byte 1 of the external damage
                                            code
              1... ....      MCEXTDXN       X'80' Bit 8 - Extended storage
                                            not operational
              .1.. ....      MCEXTDXF       X'40' Bit 9 - Extended storage
                                            control failure
    00A2  162 Bitstring    1 MCKHXDC2       Byte 2 of the external damage
                                            code
              1... ....      MCEXTDPS       X'80' Bit 16 - Primary-Sync
                                            Damage
              .1.. ....      MCEXTDEA       X'40' Bit 17 - ETR Attachement
                                            Damage
              ..1. ....      MCEXTDSL       X'20' Bit 18 - Switch to local
              ...1 ....      MCEXTDES       X'10' Bit 19 - ETR Sync check
    00A3  163 Bitstring    1 MCKHXDC3       Byte 3 of the external damage
                                            code
              .... ....      MCEXTD3        X'00' No bits defined
    00A4  164 Signed       4 MCKGXDC (0)    Guest external damage code
    00A4  164 Bitstring    1 MCKGXDC0       Byte 0 of the external damage
                                            code
              .... ....      MCEXTD0        X'00' No bits defined
    00A5  165 Bitstring    1 MCKGXDC1       Byte 1 of the external damage
                                            code
              1... ....      MCEXTDXN       X'80' Bit 8 - Extended storage
                                            not operational
              .1.. ....      MCEXTDXF       X'40' Bit 9 - Extended storage
                                            control failure
    00A6  166 Bitstring    1 MCKGXDC2       Byte 2 of the external damage
                                            code
              1... ....      MCEXTDPS       X'80' Bit 16 - Primary-Sync
                                            Damage
              .1.. ....      MCEXTDEA       X'40' Bit 17 - ETR Attachement
                                            Damage
              ..1. ....      MCEXTDSL       X'20' Bit 18 - Switch to local
              ...1 ....      MCEXTDES       X'10' Bit 19 - ETR Sync check
    00A7  167 Bitstring    1 MCKGXDC3       Byte 3 of the external damage
                                            code
              .... ....      MCEXTD3        X'00' No bits defined
    00A8  168 Dbl-Word     8 * (0)
    00A8  168 Bitstring   64 MCKMCHSV (0)   SAVE AREA FOR HCPMCH AND HCPMCS
                                            USE ONLY
    00A8  168 Signed       4 MCKMCHR0       SAVE REGISTER 0.
    00AC  172 Signed       4 MCKMCHR1       SAVE REGISTER 1.
    00B0  176 Signed       4 MCKMCHR2       SAVE REGISTER 2.
    00B4  180 Signed       4 MCKMCHR3       SAVE REGISTER 3.
    00B8  184 Signed       4 MCKMCHR4       SAVE REGISTER 4.
    00BC  188 Signed       4 MCKMCHR5       SAVE REGISTER 5.
    00C0  192 Signed       4 MCKMCHR6       SAVE REGISTER 6.
    00C4  196 Signed       4 MCKMCHR7       SAVE REGISTER 7.
    00C8  200 Signed       4 MCKMCHR8       SAVE REGISTER 8.
    00CC  204 Signed       4 MCKMCHR9       SAVE REGISTER 9.
    00D0  208 Signed       4 MCKMCHRA       SAVE REGISTER 10.
    00D4  212 Signed       4 MCKMCHRB       SAVE REGISTER 11.
    00D8  216 Signed       4 MCKMCHRC       SAVE REGISTER 12.
    00DC  220 Signed       4 MCKMCHRD       SAVE REGISTER 13.
    00E0  224 Signed       4 MCKMCHRE       SAVE REGISTER 14.
    00E4  228 Signed       4 MCKMCHRF       SAVE REGISTER 15.
    00E8  232 Bitstring   64 MCKMCHHI (0)   Space for high halves of the regs
                                            when stored discontinguously.
    00E8  232 Signed       4 MCKMCHH0       High Register 0
    00EC  236 Signed       4 MCKMCHH1       High Register 1
    00F0  240 Signed       4 MCKMCHH2       High Register 2
    00F4  244 Signed       4 MCKMCHH3       High Register 3
    00F8  248 Signed       4 MCKMCHH4       High Register 4
    00FC  252 Signed       4 MCKMCHH5       High Register 5
    0100  256 Signed       4 MCKMCHH6       High Register 6
    0104  260 Signed       4 MCKMCHH7       High Register 7
    0108  264 Signed       4 MCKMCHH8       High Register 8
    010C  268 Signed       4 MCKMCHH9       High Register 9
    0110  272 Signed       4 MCKMCHHA       High Register 10
    0114  276 Signed       4 MCKMCHHB       High Register 11
    0118  280 Signed       4 MCKMCHHC       High Register 12
    011C  284 Signed       4 MCKMCHHD       High Register 13
    0120  288 Signed       4 MCKMCHHE       High Register 14
    0124  292 Signed       4 MCKMCHHF       High Register 15
    00A8  168 Bitstring  128 MCKMCHSG (0)   Large register savearea for
                                            MCH/MCS only when storage
                                            continguously.
    00A8  168 Signed       8 MCKMCHG0       Save register 0
    00B0  176 Signed       8 MCKMCHG1       Save register 1
    00B8  184 Signed       8 MCKMCHG2       Save register 2
    00C0  192 Signed       8 MCKMCHG3       Save register 3
    00C8  200 Signed       8 MCKMCHG4       Save register 4
    00D0  208 Signed       8 MCKMCHG5       Save register 5
    00D8  216 Signed       8 MCKMCHG6       Save register 6
    00E0  224 Signed       8 MCKMCHG7       Save register 7
    00E8  232 Signed       8 MCKMCHG8       Save register 8
    00F0  240 Signed       8 MCKMCHG9       Save register 9
    00F8  248 Signed       8 MCKMCHGA       Save register 10
    0100  256 Signed       8 MCKMCHGB       Save register 11
    0108  264 Signed       8 MCKMCHGC       Save register 12
    0110  272 Signed       8 MCKMCHGD       Save register 13
    0118  280 Signed       8 MCKMCHGE       Save register 14
    0120  288 Signed       8 MCKMCHGF       Save register 15
    0128  296 Signed       8 MCKGMSG (0)    Machine check message buffer
    0128  296 Signed       4 MCKMSG (0)     MACHINE CHECK MESSAGE BUFFER.
    0128  296 Character    6 MCKHDR         FIXED MESSAGE HEADER.
    012E  302 Character   68 MCKTEXT        Variable message text.
    0172  370 Bitstring    1 MCK824CD       IDENTIFIES TEXT FOR MSG MCH824E.
    0173  371 Bitstring    1 MCK825CD       IDENTIFIES TEXT FOR MSG MCH825E.
    0174  372 Signed       4 MCKMCVBK       Address of (copy of) MCVBK
    0178  376 Signed       4 MCKWNSKP       Address of VMDBK already
                                            presented with the machine check.
    017C  380 Bitstring    1 MCKEND (0)     END OF MCKAREA.
              0000017C       MCKLEN         *-MCKBK LENGTH (BYTES) OF MCKBK.
              00000030       MCKSIZE        (MCKLEN+7)/8 SIZE (DBLWDS) OF
                                            MCKBK.
    0060   96 Bitstring    6 MCKTRCIC (0)   Bytes 0-5 of MCIC.
    0060   96 Bitstring    2 MCKTRCI0       Bytes 0-1 of MCIC.
    0062   98 Bitstring    4 MCKTRCI2       Bytes 2-5 of MCIC.
    0066  102 Bitstring    1 MCKTRCF1       BIT FLAGS OF LOCAL TRACE TABLE
                                            ENTRY.
              1... ....      MCKTRCPM       X'80' PRIMARY (NOT 2NDARY)
                                            MCH-CHK OR CHK-STP.
              .1.. ....      MCKTRCCS       X'40' ERROR WAS CHECK-STOP, NOT
                                            MACHINE CHK.
              .... ...1      MCKTRCSI       X'01' PFXHSIE FLAG WAS ON
                                            (RUNNING IN SIE).
    0067  103 Bitstring    1 *              RESERVED FOR FUTURE IBM USE.
    0068  104 Signed       4 MCKTRCTD       1ST 4 BYTES FROM TOD CLOCK. (THIS
                                            IS STORED ONLY IN PRIMARY
                                            ENTRIES, NOT SECONDARY.)
    006C  108 Signed       4 MCKTRCIA       INSTRUCTION ADDRESS FROM MCH OLD
                                            PSW.
                 Save orginal Program new PSW for VOP interception
    00E0  224 Dbl-Word     8 MCKOPNP        Saved original Program new PSW
    00D8  216 Bitstring   16 MCKOGPNP       z/Arch original Program New PSW

#### MCKBK Storage Layout

    *** MCKBK - MACHINE CHECK DESCRIPTOR BLOCK
    *
    *     +-------------+-------------+-------------+-------------+
    *   0 |  MCKCNT2N   |  MCKCNTEQ   |   MCKCNT    |  MCKHOTMK   |
    *     +------+------+------+------+------+------+------+------+
    *   8 |:FMISC|//////|:FETYP|:FTERM|//////|:FOOT5|:FOOT6|:FOOT7|
    *     +------+------+------+------+------+------+------+------+
    *  10 |                       MCKCTIMR                        |
    *     +-------------------------------------------------------+
    *  18 |                       MCKCCOMP                        |
    *     +-------------------------------------------------------+
    *  20 |                       MCKTRC1                         |
    *     |                                                       |
    *     +-------------------------------------------------------+
    *  30 |                       MCKTRC2                         |
    *     |                                                       |
    *     +-------------------------------------------------------+
    *  40 |                       MCKTRC3                         |
    *     |                                                       |
    *     +-------------------------------------------------------+
    *  50 |                       MCKTRC4                         |
    *     |                                                       |
    *     +-------------------------------------------------------+
    *  60 |                       MCKTRCUR                        |
    *     |                                                       |
    *     +---------------------------+-------------+-------------+
    *  70 |///////////////////////////|/////////////|  MCKCPUAD   |
    *     +---------------------------+------+------+------+------+
    *  78 |          MCKREC           |:FAILF|:RECFL|:IACR |:IACE |
    *     +---------------------------+------+------+------+------+
    *  80 |         MCKHNDL2          |         MCKC14SV          |
    *     +---------------------------+---------------------------+
    *  88 |         MCKTODR2          |         MCKTODR1          |
    *     +------+------+------+------+------+------+-------------+
    *  90 |:HIC0 |:HIC1 |:HIC2 |:HIC3 |:HIC4 |:HIC5 |  MCKHIC6    |
    *     +------+------+------+------+------+------+-------------+
    *  98 |:GIC0 |:GIC1 |:GIC2 |:GIC3 |:GIC4 |:GIC5 |  MCKGIC6    |
    *     +------+------+------+------+------+------+------+------+
    *  A0 |:HXDC0|:HXDC1|:HXDC2|:HXDC3|:GXDC0|:GXDC1|:GXDC2|:GXDC3|
    *     +------+------+------+------+------+------+------+------+
    *  A8 |         MCKMCHR0          |         MCKMCHR1          |
    *     +---------------------------+---------------------------+
    *  B0 |         MCKMCHR2          |         MCKMCHR3          |
    *     +---------------------------+---------------------------+
    *  B8 |         MCKMCHR4          |         MCKMCHR5          |
    *     +---------------------------+---------------------------+
    *  C0 |         MCKMCHR6          |         MCKMCHR7          |
    *     +---------------------------+---------------------------+
    *  C8 |         MCKMCHR8          |         MCKMCHR9          |
    *     +---------------------------+---------------------------+
    *  D0 |         MCKMCHRA          |         MCKMCHRB          |
    *     +---------------------------+---------------------------+
    *  D8 |         MCKMCHRC          |         MCKMCHRD          |
    *     +---------------------------+---------------------------+
    *  E0 |         MCKMCHRE          |         MCKMCHRF          |
    *     +---------------------------+---------------------------+
    *  E8 |         MCKMCHH0          |         MCKMCHH1          |
    *     +---------------------------+---------------------------+
    *  F0 |         MCKMCHH2          |         MCKMCHH3          |
    *     +---------------------------+---------------------------+
    *  F8 |         MCKMCHH4          |         MCKMCHH5          |
    *     +---------------------------+---------------------------+
    * 100 |         MCKMCHH6          |         MCKMCHH7          |
    *     +---------------------------+---------------------------+
    * 108 |         MCKMCHH8          |         MCKMCHH9          |
    *     +---------------------------+---------------------------+
    * 110 |         MCKMCHHA          |         MCKMCHHB          |
    *     +---------------------------+---------------------------+
    * 118 |         MCKMCHHC          |         MCKMCHHD          |
    *     +---------------------------+---------------------------+
    * 120 |         MCKMCHHE          |         MCKMCHHF          |
    *     +---------------------------+---------------------------+
    * 128
    *
    *** MCKBK - MACHINE CHECK DESCRIPTOR BLOCK

    *** Overlay for MCKMCHSV in MCKBK
    *
    *     +-------------------------------------------------------+
    *  A8 |                       MCKMCHG0                        |
    *     +-------------------------------------------------------+
    *  B0 |                       MCKMCHG1                        |
    *     +-------------------------------------------------------+
    *  B8 |                       MCKMCHG2                        |
    *     +-------------------------------------------------------+
    *  C0 |                       MCKMCHG3                        |
    *     +-------------------------------------------------------+
    *  C8 |                       MCKMCHG4                        |
    *     +-------------------------------------------------------+
    *  D0 |                       MCKMCHG5                        |
    *     +-------------------------------------------------------+
    *  D8 |                       MCKMCHG6                        |
    *     +-------------------------------------------------------+
    *  E0 |                       MCKMCHG7                        |
    *     +-------------------------------------------------------+
    *  E8 |                       MCKMCHG8                        |
    *     +-------------------------------------------------------+
    *  F0 |                       MCKMCHG9                        |
    *     +-------------------------------------------------------+
    *  F8 |                       MCKMCHGA                        |
    *     +-------------------------------------------------------+
    * 100 |                       MCKMCHGB                        |
    *     +-------------------------------------------------------+
    * 108 |                       MCKMCHGC                        |
    *     +-------------------------------------------------------+
    * 110 |                       MCKMCHGD                        |
    *     +-------------------------------------------------------+
    * 118 |                       MCKMCHGE                        |
    *     +-------------------------------------------------------+
    * 120 |                       MCKMCHGF                        |
    *     +-----------------------------------------+-------------+
    * 128 |                 MCKHDR                  |             |
    *     +-----------------------------------------+             |
    * 130 |                                                       |
    *     =                       MCKTEXT                         =
    *     |             +------+------+---------------------------+
    * 170 |             |:824CD|:825CD|         MCKMCVBK          |
    *     +-------------+------+------+---------------------------+
    * 178 |         MCKWNSKP          |
    *     +---------------------------+
    *
    *** Overlay for MCKMCHSV in MCKBK

    *** Overlay for MCKTRCUR in MCKBK
    *
    *     +-------------+---------------------------+------+------+
    *  60 |  MCKTRCI0   |         MCKTRCI2          |:TRCF1|//////|
    *     +-------------+-------------+-------------+------+------+
    *  68 |         MCKTRCTD          |         MCKTRCIA          |
    *     +---------------------------+---------------------------+
    *  70
    *
    *** Overlay for MCKTRCUR in MCKBK

    *** Overlay for MCKMCHRE in MCKBK
    *
    *     +-------------------------------------------------------+
    *  E0 |                       MCKOPNP                         |
    *     +-------------------------------------------------------+
    *  E8
    *
    *** Overlay for MCKMCHRE in MCKBK

    *** Overlay for MCKMCHRC in MCKBK
    *
    *     +-------------------------------------------------------+
    *  D8 |                       MCKOGPNP                        |
    *     |                                                       |
    *     +-------------------------------------------------------+
    *  E8
    *
    *** Overlay for MCKMCHRC in MCKBK

#### MCKBK Cross Reference

    Symbol         Dspl Value
    -------------- ---- -----
    MCEXTDEA       00A2 40
    MCEXTDEA       00A6 40
    MCEXTDES       00A2 10
    MCEXTDES       00A6 10
    MCEXTDPS       00A2 80
    MCEXTDPS       00A6 80
    MCEXTDSL       00A2 20
    MCEXTDSL       00A6 20
    MCEXTDXF       00A1 40
    MCEXTDXF       00A5 40
    MCEXTDXN       00A1 80
    MCEXTDXN       00A5 80
    MCEXTD0        00A0 00
    MCEXTD0        00A4 00
    MCEXTD3        00A3 00
    MCEXTD3        00A7 00
    MCICAR         0095 08
    MCICAR         009D 08
    MCICBU         0091 02
    MCICBU         0099 02
    MCICCD         0090 08
    MCICCD         0098 08
    MCICCRW        0091 40
    MCICCRW        0099 40
    MCICCSD        0091 10
    MCICCSD        0099 10
    MCICDG         0090 01
    MCICDG         0098 01
    MCICDL         0091 01
    MCICDL         0099 01
    MCICED         0090 04
    MCICED         0098 04
    MCICITD        0090 10
    MCICITD        0098 10
    MCICKE         0092 20
    MCICKE         009A 20
    MCICPD         0090 40
    MCICPD         0098 40
    MCICSC         0092 40
    MCICSC         009A 40
    MCICSD         0090 80
    MCICSD         0098 80
    MCICSDG        0092 10
    MCICSDG        009A 10
    MCICSE         0092 80
    MCICSE         009A 80
    MCICSP         0091 20
    MCICSP         0099 20
    MCICSR         0090 20
    MCICSR         0098 20
    MCICVCC        0095 01
    MCICVCC        009D 01
    MCICVCR        0093 04
    MCICVCR        009B 04
    MCICVCT        0095 02
    MCICVCT        009D 02
    MCICVED        0093 20
    MCICVED        009B 20
    MCICVFA        0093 80
    MCICVFA        009B 80
    MCICVFP        0093 10
    MCICVFP        009B 10
    MCICVGR        0093 08
    MCICVGR        009B 08
    MCICVIA        0092 01
    MCICVIA        009A 01
    MCICVLG        0093 02
    MCICVLG        009B 02
    MCICVMS        0092 04
    MCICVMS        009A 04
    MCICVPM        0092 02
    MCICVPM        009A 02
    MCICVST        0093 01
    MCICVST        009B 01
    MCICVTPR       0095 20
    MCICVTPR       009D 20
    MCICVWP        0092 08
    MCICVWP        009A 08
    MCICVXFP       0095 10
    MCICVXFP       009D 10
    MCICW          0091 80
    MCICW          0099 80
    MCIPRIM0       0090 FF
    MCIPRIM0       0098 FF
    MCIPRIM1       0091 F0
    MCIPRIM1       0099 F0
    MCKCCOMP       0018
    MCKCLEAR       0090
    MCKCLKS        0010
    MCKCNT         0004
    MCKCNTEQ       0002
    MCKCNT2N       0000
    MCKCPREC       007D 80
    MCKCPUAD       0076
    MCKCTIMR       0010
    MCKC14SV       0084
    MCKDAMAG       0000
    MCKDEGRN       007C 04
    MCKDEGRP       007C 08
    MCKDLEN        0076 00000078
    MCKDSIZE       0076 0000000F
    MCKEND         017C
    MCKFABND       000A 04
    MCKFAILF       007C
    MCKFATSK       000F 80
    MCKFDIE1       000B 20
    MCKFDIE2       000B 10
    MCKFEMER       000B 80
    MCKFERCS       000A 40
    MCKFETYP       000A
    MCKFHOT        0008 20
    MCKFIPL        000B 08
    MCKFIPLI       000B 04
    MCKFIXUP       0008 80
    MCKFLAGS       0008
    MCKFMCIC       000A 08
    MCKFMISC       0008
    MCKFNOTM       000B 40
    MCKFOOT5       000D
    MCKFOOT6       000E
    MCKFOOT7       000F
    MCKFORCE       007C 40
    MCKFRMOF       000F 20
    MCKFSIE        0008 40
    MCKFTERM       000B
    MCKFVFIX       000D 80
    MCKFXCKC       000E 20
    MCKFXCTL       000E 80
    MCKFXKEY       000F 10
    MCKFXPAG       000F 08
    MCKFXPT        000E 10
    MCKFXTPR       000E 08
    MCKFXTSK       000F 40
    MCKFZTOD       000D 40
    MCKF2CS        000A 10
    MCKF2ND        000A 20
    MCKGIC         0098
    MCKGIC0        0098
    MCKGIC1        0099
    MCKGIC2        009A
    MCKGIC3        009B
    MCKGIC4        009C
    MCKGIC5        009D
    MCKGIC6        009E
    MCKGMSG        0128
    MCKGXDC        00A4
    MCKGXDC0       00A4
    MCKGXDC1       00A5
    MCKGXDC2       00A6
    MCKGXDC3       00A7
    MCKHARD        007C 10
    MCKHDR         0128
    MCKHIC         0090
    MCKHIC0        0090
    MCKHIC1        0091
    MCKHIC2        0092
    MCKHIC3        0093
    MCKHIC4        0094
    MCKHIC5        0095
    MCKHIC6        0096
    MCKHNDL2       0080
    MCKHOTMK       0006
    MCKHXDC        00A0
    MCKHXDC0       00A0
    MCKHXDC1       00A1
    MCKHXDC2       00A2
    MCKHXDC3       00A3
    MCKIACE        007F
    MCKIACR        007E
    MCKLEN         017C 0000017C
    MCKLFREC       007D 40
    MCKMCHGA       00F8
    MCKMCHGB       0100
    MCKMCHGC       0108
    MCKMCHGD       0110
    MCKMCHGE       0118
    MCKMCHGF       0120
    MCKMCHG0       00A8
    MCKMCHG1       00B0
    MCKMCHG2       00B8
    MCKMCHG3       00C0
    MCKMCHG4       00C8
    MCKMCHG5       00D0
    MCKMCHG6       00D8
    MCKMCHG7       00E0
    MCKMCHG8       00E8
    MCKMCHG9       00F0
    MCKMCHHA       0110
    MCKMCHHB       0114
    MCKMCHHC       0118
    MCKMCHHD       011C
    MCKMCHHE       0120
    MCKMCHHF       0124
    MCKMCHHI       00E8
    MCKMCHH0       00E8
    MCKMCHH1       00EC
    MCKMCHH2       00F0
    MCKMCHH3       00F4
    MCKMCHH4       00F8
    MCKMCHH5       00FC
    MCKMCHH6       0100
    MCKMCHH7       0104
    MCKMCHH8       0108
    MCKMCHH9       010C
    MCKMCHRA       00D0
    MCKMCHRB       00D4
    MCKMCHRC       00D8
    MCKMCHRD       00DC
    MCKMCHRE       00E0
    MCKMCHRF       00E4
    MCKMCHR0       00A8
    MCKMCHR1       00AC
    MCKMCHR2       00B0
    MCKMCHR3       00B4
    MCKMCHR4       00B8
    MCKMCHR5       00BC
    MCKMCHR6       00C0
    MCKMCHR7       00C4
    MCKMCHR8       00C8
    MCKMCHR9       00CC
    MCKMCHSG       00A8
    MCKMCHSV       00A8
    MCKMCVBK       0174
    MCKMSG         0128
    MCKOGPNP       00D8
    MCKOPNP        00E0
    MCKPASS        007C 02
    MCKREC         0078
    MCKRECFL       007D
    MCKSIZE        017C 00000030
    MCKSOFT        007C 01
    MCKSOMIN       007C 80
    MCKTEXT        012E
    MCKTHLD1       0002 00000009
    MCKTHLD2       0004 0000000A
    MCKTIM1        0002 00000258
    MCKTIM2        0004 0000012C
    MCKTODR1       008C
    MCKTODR2       0088
    MCKTRC         0020
    MCKTRCCS       0066 40
    MCKTRCF1       0066
    MCKTRCIA       006C
    MCKTRCIC       0060
    MCKTRCI0       0060
    MCKTRCI2       0062
    MCKTRCPM       0066 80
    MCKTRCSI       0066 01
    MCKTRCTD       0068
    MCKTRCUR       0060
    MCKTRCZ        0060 00000070
    MCKTRC1        0020
    MCKTRC2        0030
    MCKTRC3        0040
    MCKTRC4        0050
    MCKWNSKP       0178
    MCK824CD       0172
    MCK825CD       0173

This information is based on z/VM V5R2.0. Last updated on 12 Apr 2006 at 17:04:20 EDT.
Copyright IBM Corporation, 1990, 2005