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

#### DRWBK

Prolog

Control Block Contents
DRWBK DSECT

Storage Layout

Cross Reference (Contains links to field and bit definitions)

#### DRWBK Prolog

     NAME       : HCPDRWBK
     DESCRIPTION: DASD Read/Write Channel Program Block
     DSECT      : DRWBK
     FUNCTION   : This DSECT maps the channel program created
                  to process a *BLOCKIO or diagnose A4 I/O\request
     LOCATED BY : DVICHPRG field in HCPDVIOP
     CREATED BY : HCPDPSRW
     DELETED BY : HCPDPSCU
     SERIALIZED : Unique task execution
                  VMDBK dispatch lock.
                  The chain of DVIOPS is protected by the
                  BLKIO lock, in HCPBLKIO

#### DRWBK Control Block Content

#### DRWBK DSECT

    Hex   Dec Type/Val   Lng Label (dup)    Comments
    ---- ---- --------- ---- -------------- --------
    0000    0 Structure      DRWBK          DASD Read/Write Channel Program
                                            Block
    0000    0 Dbl-Word     8 DRWCHPRG (0)   Channel program segment
    0000    0 Dbl-Word     8 DRWSEEK        SEEK CCW
    0008    8 Dbl-Word     8 DRWSSECT       SET SECTOR CCW
    0010   16 Dbl-Word     8 DRWSRCH        SEARCH ID CCW
    0018   24 Dbl-Word     8 DRWTIC1        TIC CCW
    0020   32 Dbl-Word     8 DRWRDWR        READ/WRITE CCW
    0028   40 Dbl-Word     8 DRWTIC2        TIC CCW
              00000030       DRWCHPSZ       *-DRWCHPRG
    0030   48 Bitstring   12 DRWDATA (0)    Data area portion of channel
                                            program Segment
    0030   48 Bitstring    6 DRWSKARG (0)   SEEK argument (BBCCHH)
    0030   48 Bitstring    2 DRWSKBIN       SEEK: bin (BB) number
    0032   50 Bitstring    2 DRWSKCYL       SEEK: cylinder (CC) number
    0034   52 Bitstring    2 DRWSKHED       SEEK: head/track (HH) number
    0036   54 Bitstring    5 DRWSRCAR (0)   SEARCH ID equal argument (CCHHR)
    0036   54 Bitstring    2 DRWSRCYL       SEARCH: cylinder (CC) number
    0038   56 Bitstring    3 DRWSRHHR (0)   SEARCH: head + record (HHR)
    0038   56 Bitstring    2 DRWSRHED       SEARCH: head/track (HH) number
    003A   58 Bitstring    1 DRWSRREC       SEARCH: record (R) number
    003B   59 Bitstring    1 DRWSECTR       SET SECTOR: sector number
    003C   60 Signed       4 *              Reserved for IBM use
              00000040       DRWBSIZE       *-DRWCHPRG Byte size of channel
                                            program (CCWs plus data area)
              00000008       DRWSIZE        (DRWBSIZE+7)/8 Doubleword size of
                                            channel program (CCWs plus data
                                            area)
    0040   64 Dbl-Word     8 DRWNXTSG (0)   Start of next channel program
                                            segment

#### DRWBK Storage Layout

    *** DRWBK - DASD Read/Write Channel Program Block
    *
    *     +-------------------------------------------------------+
    *   0 |                       DRWSEEK                         |
    *     +-------------------------------------------------------+
    *   8 |                       DRWSSECT                        |
    *     +-------------------------------------------------------+
    *  10 |                       DRWSRCH                         |
    *     +-------------------------------------------------------+
    *  18 |                       DRWTIC1                         |
    *     +-------------------------------------------------------+
    *  20 |                       DRWRDWR                         |
    *     +-------------------------------------------------------+
    *  28 |                       DRWTIC2                         |
    *     +-------------+-------------+-------------+-------------+
    *  30 |  DRWSKBIN   |  DRWSKCYL   |  DRWSKHED   |  DRWSRCYL   |
    *     +-------------+------+------+-------------+-------------+
    *  38 |  DRWSRHED   |:SRREC|:SECTR|///////////////////////////|
    *     +-------------+------+------+---------------------------+
    *
    *** DRWBK - DASD Read/Write Channel Program Block

#### DRWBK Cross Reference

    Symbol         Dspl Value
    -------------- ---- -----
    DRWBSIZE       003C 00000040
    DRWCHPRG       0000
    DRWCHPSZ       0028 00000030
    DRWDATA        0030
    DRWNXTSG       0040
    DRWRDWR        0020
    DRWSECTR       003B
    DRWSEEK        0000
    DRWSIZE        003C 00000008
    DRWSKARG       0030
    DRWSKBIN       0030
    DRWSKCYL       0032
    DRWSKHED       0034
    DRWSRCAR       0036
    DRWSRCH        0010
    DRWSRCYL       0036
    DRWSRHED       0038
    DRWSRHHR       0038
    DRWSRREC       003A
    DRWSSECT       0008
    DRWTIC1        0018
    DRWTIC2        0028

This information is based on z/VM V5R2.0. Last updated on 12 Apr 2006 at 16:51:37 EDT.
Copyright IBM Corporation, 1990, 2005