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

#### CHCBK

Prolog

Control Block Contents
CHCBK DSECT

Storage Layout

Cross Reference (Contains links to field and bit definitions)

#### CHCBK Prolog

     NAME       : HCPCHCBK
     DESCRIPTION: CHANNEL CLASS BLOCK
     DSECT      : CHCBK
     FUNCTION   : DESCRIBE THE STATUS OF THE CHANNELS ( IN XA MODE, THE
                  CHANNEL CLASSES) FOR A VIRTUAL MACHINE.
                  ANCHOR THE QUEUE OF DEVICES (FOR EACH CHANNEL NUMBER OR
                  CLASS) FOR WHICH INTERRUPTS ARE PENDING.
     LOCATED BY : VMDCHC FIELD IN THE VIRTUAL MACHINE'S DEFINITION BLOCK
     CREATED BY : VIRTUAL MACHINE CREATION PROCESS - HCPBVM
     DELETED BY : VIRTUAL MACHINE DESTRUCTION PROCESS

#### CHCBK Control Block Content

#### CHCBK DSECT

    Hex   Dec Type/Val   Lng Label (dup)    Comments
    ---- ---- --------- ---- -------------- --------
    0000    0 Structure      CHCBK          CHANNEL CLASS BLOCK
    0000    0 Dbl-Word     8 CHCLOCK (0)    LOCKWORD FOR THIS BLOCK
    0000    0 Address      4 CHCLOWNR       ADDRESS OF OWNING VMDBK
    0004    4 Address      4 CHCLOCWQ       QUEUE OF WAITING TASKS
    0008    8 Signed       4 *              Reserved for future IBM use
                                      SET-CHANNEL-MONITOR DOUBLEWORD
                                      THE FOLLOWING  FIELDS  CONTROL
                                      GUEST CHANNEL MONITORING. THEY
                                      ARE KEPT WITHIN  A  DOUBLEWORD
                                      TO ALLOW  A  STORE-MULTIPLE TO
                                      PERFORM MP-CONSISTENT  SETTING
                                      OF THE CONTROLS ON A HOST MP.
    000C   12 Signed       4 CHCKEYCN (0)   Key and control word
    000C   12 Bitstring    1 CHCKEY         KEY OF USER MEASUREMENT BLOCK
    000D   13 Bitstring    1 *              RESERVED FOR FUTURE IBM USE
    000E   14 Bitstring    1 *              RESERVED FOR FUTURE IBM USE
    000F   15 Bitstring    1 CHCHFLAG       HARDWARE CONTROLS
              .... ..1.      CHCMSM         X'02' MEASUREMENT ACTIVE
              .... ...1      CHCTIM         X'01' TIMING (SHOULD BE) ACTIVE
    0010   16 Dbl-Word     8 CHCGMBO (0)    zArch: 64 bit MBO for monitoring
    0010   16 Signed       4 CHCGMBOH       zArch: high order MBO word
    0014   20 Signed       4 CHCGMBOL       zArch: Low order MBO word
              ...1 .1..      CHCMBLKO       CHCGMBOL 390: Measurement Blk
                                            Origin
    0018   24 Signed       4 CHCIORW        POINTER TO CHAIN OF CRWBK'S.
    001C   28 Bitstring    1 CHCSFLAG       SOFTWARE CONTROLS
              1... ....      CHCRWCC1       X'80' CONDITION CODE 1 REMAINS TO
                                            BE GIVEN TO A GUEST STORE CHANNEL
                                            REPORT WORD SINCE GENERATING A
                                            MACHINE CHECK FOR A PREVIOUS
                                            CHANNEL REPORT WORD CONDITION.
                                            THIS BIT IS CLEARED BY AN I/O
                                            SYSTEM RESET. IT PREVENTS THE
                                            GENERATION OF A MACHINE CHECK FOR
                                            CHANNEL REPORT WORDS MADE
                                            PENDING.
              .1.. ....      CHCEMW         X'40'
                                            Extended-I/O-measurement-word
                                            facility enabled with CHSC Set
                                            Domain Attributes command
    001D   29 Bitstring    1 *              RESERVED FOR FUTURE IBM USE
    001E   30 Bitstring    1 *              RESERVED FOR FUTURE IBM USE
    001F   31 Bitstring    1 *              RESERVED FOR FUTURE IBM USE
    0020   32 Signed       4 CHCSALIM       SET ADDRESS LIMIT VALUE
    0024   36 Signed       4 CHCMCV         POINTER TO MCVBK. FOR FLOATING
                                            MACHINE CHECKS (THEY ARE RELATED
                                            TO THE I/O SUBSYSTEM).
    0028   40 Dbl-Word     8 *              RESERVED FOR FUTURE IBM USE
    0030   48 Signed       4 *              RESERVED FOR FUTURE IBM USE
    0034   52 Signed       4 CHCIOPND       MASK OF PENDING INTERRUPTIONS
    0038   56 Dbl-Word     8 CHCQUEUE (32)  FWD AND BWD INTERRUPT PTRS
              00000020       CHCQSIZE       (*-CHCQUEUE)/CHCQENTL DEFINE
                                            NUMBER OF CHANNELS
              00000027       CHCSIZE        (*-CHCBK+7)/8 SIZE OF FLOATING
                                            CHANNEL BLOCK
    0038   56 Signed       4 CHCQUEFW       CHANNEL INT. QUEUE FORWARD PTR
    003C   60 Signed       4 CHCQUEBW       CHANNEL INT. QUEUE BACKWARD PTR
              00000008       CHCQENTL       *-CHCQUEFW LENGTH OF QUEUE
                                            POINTERS

#### CHCBK Storage Layout

    *** CHCBK - CHANNEL CLASS BLOCK
    *
    *     +---------------------------+---------------------------+
    *   0 |         CHCLOWNR          |         CHCLOCWQ          |
    *     +---------------------------+------+------+------+------+
    *   8 |///////////////////////////|CHCKEY|//////|//////|:HFLAG|
    *     +---------------------------+------+------+------+------+
    *  10 |         CHCGMBOH          |         CHCGMBOL          |
    *     +---------------------------+------+------+------+------+
    *  18 |         CHCIORW           |:SFLAG|//////|//////|//////|
    *     +---------------------------+------+------+------+------+
    *  20 |         CHCSALIM          |          CHCMCV           |
    *     +---------------------------+---------------------------+
    *  28 |///////////////////////////////////////////////////////|
    *     +---------------------------+---------------------------+
    *  30 |///////////////////////////|         CHCIOPND          |
    *     +---------------------------+---------------------------+
    *  38 |                                                       |
    *     =                       CHCQUEUE                        =
    *     |                                                       |
    *     +-------------------------------------------------------+
    * 138
    *
    *** CHCBK - CHANNEL CLASS BLOCK

    *** Overlay for CHCQUEUE in CHCBK
    *
    *     +---------------------------+---------------------------+
    *  38 |         CHCQUEFW          |         CHCQUEBW          |
    *     +---------------------------+---------------------------+
    *  40
    *
    *** Overlay for CHCQUEUE in CHCBK

#### CHCBK Cross Reference

    Symbol         Dspl Value
    -------------- ---- -----
    CHCEMW         001C 40
    CHCGMBO        0010
    CHCGMBOH       0010
    CHCGMBOL       0014
    CHCHFLAG       000F
    CHCIOPND       0034
    CHCIORW        0018
    CHCKEY         000C
    CHCKEYCN       000C
    CHCLOCK        0000
    CHCLOCWQ       0004
    CHCLOWNR       0000
    CHCMBLKO       0014 14
    CHCMCV         0024
    CHCMSM         000F 02
    CHCQENTL       003C 00000008
    CHCQSIZE       0038 00000020
    CHCQUEBW       003C
    CHCQUEFW       0038
    CHCQUEUE       0038
    CHCRWCC1       001C 80
    CHCSALIM       0020
    CHCSFLAG       001C
    CHCSIZE        0038 00000027
    CHCTIM         000F 01

This information is based on z/VM V5R2.0. Last updated on 12 Apr 2006 at 16:43:29 EDT.
Copyright IBM Corporation, 1990, 2005