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

#### EXPBK

Prolog

Control Block Contents
EXPBK DSECT
EXPQUENT DSECT

Storage Layout

Cross Reference (Contains links to field and bit definitions)

#### EXPBK Prolog

     NAME       : HCPEXPBK
     DESCRIPTION: EXPOSURE BLOCK
     DSECT      : EXPBK
     FUNCTION   : The exposure block contains necessary information
                  about a CP volume for paging information.
     LOCATED BY : CPVEXPBK - For single exposure devices, points to
                  the exposure block.
                  For multiple exposure devices, points to
                  the first one of a contiguous group.
     CREATED BY : HCPRDAAT - When the CP owned volume is brought on
                  line at IPL time and during the ATTACH
                  command processing.
     DELETED BY : HCPRDADT - When the CP owned volume is DETACHed from
                  the system.
     SERIALIZED : EXPLCKFG - A Test and Set instruction is used to set
                  the lock flag on to serialize this control
                  block and the IORBK control block for the
                  exposure.
     COMMENTS   :
                  Each logical path to a device is an exposure.
                  One device may have several exposures.  If so,
                  each exposure has its own EXPBK, and all the EXPBKs
                  for a single device are located in contiguous
                  storage.

#### EXPBK Control Block Content

#### EXPBK DSECT

####

####

####

    Hex   Dec Type/Val   Lng Label (dup)    Comments
    ---- ---- --------- ---- -------------- --------
    0000    0 Structure      EXPBK          EXPOSURE BLOCK
         Flags for the exposure block.
    0000    0 Signed       4 EXPFLAGS (0)   Flags for the exposure block
    0000    0 Bitstring    1 EXPLCKFG       Exposure lock byte. X'FF' -
                                            Indicates this exposure is
                                            locked. X'00' - Indicates this
                                            exposure is available for use
              .... ....      EXPLCKRL       X'00' Used to release the
                                            exposure lock
         This flag is to keep the status information for this exposure.
    0001    1 Bitstring    1 EXPSTATF       Exposure status flag
              00000000       EXPNOP         X'00' Indicates that neither a
                                            RSCH or a SSCH is required.
              00000001       EXPDQINP       X'01' Indicates a DEQUEUE in
                                            progress
              00000002       EXPRSCH        X'02' Indicates that a RSCH is
                                            required
              00000004       EXPSSCH        X'04' Indicates that a SSCH is
                                            required
    0002    2 Bitstring    1 EXPTYPEF       Exposure type flag
              .... ..1.      EXPFBA         X'02' This is an FBA device
              .... ...1      EXPECKD        X'01' Indicates this is an ECKD
                                            paging device
    0003    3 Bitstring    1 *              Reserved for future IBM use
         Maximum number of outstanding DASD I/O for multiple read or writes.
    0004    4 Signed       2 EXPMAXMW       Maximum number of multiple writes
                                            that can be added into the
                                            channel program. This value is 4
                                            * number of records per track.
    0006    6 Signed       2 EXPQCNEG       Number of times EXPCURQC went
                                            neg.
         The IORBK for this exposure
    0008    8 Address      4 EXPFACPA       First Active Channel Program Addr
    000C   12 Address      4 EXPSCCWP       Suspended CCW package. This is
                                            also the address of the last
                                            PIOBK in the current channel
                                            program.
         These are deferred saveareas when all CCW packages are used for this
         exposure. The saveareas are a single threaded list with the last
         pointer equal to zero.
    0010   16 Address      4 EXPSFDSV       First deferred savearea for
                                            single reads and writes
    0014   20 Address      4 EXPSCDSV       Current deferred savearea that
                                            will be dequeue for single reads
                                            and write
    0018   24 Address      4 EXPMRDFQ       Queue anchor for deferred
                                            multiple read operations which
                                            are sorted in ascending order by
                                            cylinder number. The end of queue
                                            is zeroes
    001C   28 Address      4 EXPMRCQ        Address of the current deferred
                                            read SAVBK which is the current
                                            active cylinder number.
    0020   32 Address      4 EXPMWDFQ       Queue anchor for deferred
                                            multiple write operations which
                                            are sorted in ascending order by
                                            cylinder number. The end of queue
                                            is zeroes
    0024   36 Address      4 EXPMWCQ        Address of the current deferred
                                            write SAVBK which is the current
                                            active cylinder number.
         Monitor counters.
    0028   40 Signed       4 EXPCTPRD       Total count of page read
                                            operations for this device. Note
                                            that page read operations may be
                                            directed to devices without any
                                            cylinders specifically defined as
                                            type PAGE.
    002C   44 Signed       4 EXPCTPWR       Total count of page write
                                            operations for this device. Note
                                            that page write operations may be
                                            directed to devices without any
                                            cylinders specifically defined as
                                            type PAGE.
    0030   48 Signed       4 EXPCTSRD       Total count of spooling reads for
                                            this device.
    0034   52 Signed       4 EXPCTSWR       Total count of spooling writes
                                            for this device.
    0038   56 Signed       4 EXPCTACP       Total count of paging/spooling
                                            reads and writes added to an
                                            existing channel program without
                                            executing a SSCH or RSCH.
    003C   60 Signed       4 EXPCURQC       Cardinal count of all outstanding
                                            paging/spooling reads/writes for
                                            this device.
    0040   64 Signed       4 EXP2BQED       Count of slots that have been
                                            assigned on this CPVOL but have
                                            not yet been added to EXPCURQC
                                            (CPVOL because EXP2BQED is only
                                            valid in the first EXPBK for
                                            multi exposure devices). This
                                            count is updated using CS logic
    0044   68 Address      4 EXPIORBK       IORBK for this exposure. The
                                            IORBK is always at the beginning
                                            of each PAGBK so this field
                                            doubles as the PAGBK address
              00000044       EXPPAGBK       EXPIORBK,4 PAGBK for this
                                            exposure
    0048   72 Signed       4 EXPCTUSI       Total count of the number of
                                            times the channel program had to
                                            be terminated to allow user I/O.
                                            This is an indicator of
                                            interference between user and
                                            paging/spooling I/O.
    004C   76 Signed       4 EXPDEVST       Exposure service time.
    0050   80 Signed       4 EXPMLOAD       Exposure MLOAD.
    0054   84 Signed       4 EXPTIMER       Exposure timestamp for SSCH/RSCH.
    0058   88 Signed       4 EXPINTIM       Exposure timestamp at I/O
                                            interrupt time. ....
    005C   92 Signed       4 EXPNMPIO       Number of active PIOBKS at I/O
                                            interrupt time used to calc
                                            service time.
    0060   96 Address      4 EXPRDCBK       Address of the RDCBK.
    0064  100 Signed       4 EXPCONT (20)   Count of 20 contiguous free
                                            spaces allocated from 1 to 20
                                            plus.
    00B4  180 Signed       4 EXPBKEND (0)   End of EXPBK.
              000000B4       EXPBSIZE       *-EXPBK Size of this DSECT in
                                            Bytes
              00000017       EXPSIZE        (((*-EXPBK)+7)/8) Size in
                                            double-words
         The next three statements EXPQUENT, EXPQANCH, and EXPQCURR are used to
         map the multiple read and write queue fields EXPMRDFQ, EXPMRCQ and
         EXPMWDFQ, EXPMWCQ.

    EXPQUENT DSECT

    Hex   Dec Type/Val   Lng Label (dup)    Comments
    ---- ---- --------- ---- -------------- --------
    0000    0 Structure      EXPQUENT       EXPOSURE BLOCK
    0000    0 Address      4 EXPQANCH       Anchor for multiple defer queues.
    0004    4 Address      4 EXPQCURR       Current pointer to CPEBK in
                                            queue.

    EXPBK Storage Layout

    *** EXPBK - EXPOSURE BLOCK
    *
    *     +------+------+------+------+-------------+-------------+
    *   0 |:LCKFG|:STATF|:TYPEF|//////|  EXPMAXMW   |  EXPQCNEG   |
    *     +------+------+------+------+-------------+-------------+
    *   8 |         EXPFACPA          |         EXPSCCWP          |
    *     +---------------------------+---------------------------+
    *  10 |         EXPSFDSV          |         EXPSCDSV          |
    *     +---------------------------+---------------------------+
    *  18 |         EXPMRDFQ          |         EXPMRCQ           |
    *     +---------------------------+---------------------------+
    *  20 |         EXPMWDFQ          |         EXPMWCQ           |
    *     +---------------------------+---------------------------+
    *  28 |         EXPCTPRD          |         EXPCTPWR          |
    *     +---------------------------+---------------------------+
    *  30 |         EXPCTSRD          |         EXPCTSWR          |
    *     +---------------------------+---------------------------+
    *  38 |         EXPCTACP          |         EXPCURQC          |
    *     +---------------------------+---------------------------+
    *  40 |         EXP2BQED          |         EXPIORBK          |
    *     +---------------------------+---------------------------+
    *  48 |         EXPCTUSI          |         EXPDEVST          |
    *     +---------------------------+---------------------------+
    *  50 |         EXPMLOAD          |         EXPTIMER          |
    *     +---------------------------+---------------------------+
    *  58 |         EXPINTIM          |         EXPNMPIO          |
    *     +---------------------------+---------------------------+
    *  60 |         EXPRDCBK          |                           |
    *     +---------------------------+                           |
    *  68 |                                                       |
    *     =                       EXPCONT                         =
    *     |                           +---------------------------+
    *     |                           |
    *     +---------------------------+
    *
    *** EXPBK - EXPOSURE BLOCK

    *** EXPQUENT - EXPOSURE BLOCK
    *
    *     +---------------------------+---------------------------+
    *   0 |         EXPQANCH          |         EXPQCURR          |
    *     +---------------------------+---------------------------+
    *   8
    *
    *** EXPQUENT - EXPOSURE BLOCK

    EXPBK Cross Reference

    Symbol         Dspl Value
    -------------- ---- -----
    EXPBKEND       00B4
    EXPBSIZE       00B4 000000B4
    EXPCONT        0064
    EXPCTACP       0038
    EXPCTPRD       0028
    EXPCTPWR       002C
    EXPCTSRD       0030
    EXPCTSWR       0034
    EXPCTUSI       0048
    EXPCURQC       003C
    EXPDEVST       004C
    EXPDQINP       0001 00000001
    EXPECKD        0002 01
    EXPFACPA       0008
    EXPFBA         0002 02
    EXPFLAGS       0000
    EXPINTIM       0058
    EXPIORBK       0044
    EXPLCKFG       0000
    EXPLCKRL       0000 00
    EXPMAXMW       0004
    EXPMLOAD       0050
    EXPMRCQ        001C
    EXPMRDFQ       0018
    EXPMWCQ        0024
    EXPMWDFQ       0020
    EXPNMPIO       005C
    EXPNOP         0001 00000000
    EXPPAGBK       0044 00000044
    EXPQANCH       0000
    EXPQCNEG       0006
    EXPQCURR       0004
    EXPRDCBK       0060
    EXPRSCH        0001 00000002
    EXPSCCWP       000C
    EXPSCDSV       0014
    EXPSFDSV       0010
    EXPSIZE        00B4 00000017
    EXPSSCH        0001 00000004
    EXPSTATF       0001
    EXPTIMER       0054
    EXPTYPEF       0002
    EXP2BQED       0040

    This information is
    based on z/VM V4R3.0.
    Last updated on 1 May 2002 at 09:28:09 EDT.

    Copyright IBM Corporation, 1990, 2002