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

#### DVTRK

Prolog

Control Block Contents
DVTRK DSECT

Storage Layout

Cross Reference (Contains links to field and bit definitions)

#### DVTRK Prolog

     NAME       : HCPDVTRK
     DESCRIPTION: DASD Virtual TRacK list node
     DSECT      : DVTRK
     FUNCTION   : Contains information specific to DASD block
                  I/O requests.  To be specific, this control
                  block contains information regarding a
                  particular track that was accessed (for write)
                  during the process of one CMS block i/o
                  request.  All tracks that were accessed
                  for write have one of these control blocks
                  created for them and these control blocks are
                  linked together and anchored off of the DBCWK
                  control block.
     LOCATED BY : DBCTFRST in the DBCWK control block.
                  Also, any DVIENTRY that contains a block
                  on the track represented by this DVTRK point
                  to this control block.
     CREATED BY : HCPDPCUT macro in module HCPDBC
     DELETED BY : HCPDPSRP and/or HCPDPSCU (at cleanup time
                  after an entire CMS block i/o request has
                  completed).
     COMMENTS   : None

#### DVTRK Control Block Content

#### DVTRK DSECT

    Hex   Dec Type/Val   Lng Label (dup)    Comments
    ---- ---- --------- ---- -------------- --------
    0000    0 Structure      DVTRK          DASD Virtual TRacK list node
    0000    0 Dbl-Word     8 * (0)          Better be double word aligned!
    0000    0 Address      4 DVTFORW        Pointer to next DVTRK block
    0004    4 Address      4 DVTTCHBK       TCHBK Address
    0008    8 Signed       4 DVTCOUNT       Count of unscheduled i/os to
                                            track
    000C   12 Signed       4 DVTTKDAT (0)   Track data, copied between here
                                            and HCPDBCWK, so it MUST match
    000C   12 Signed       4 DVTCDATA       TCHBK Center data word contents
    0010   16 Bitstring    1 DVTFILL        Filler, can't be used without
                                            changes to HCPDBC since data is
                                            copied directly
    0011   17 Bitstring    3 DVTDPSTF (0)   DPSBK stuff about track
    0011   17 Bitstring    1 DVTHIRN        Highest record num on track
    0012   18 Signed       2 *              Reserved for IBM use
              00000002       DVTTKLEN       (*-DVTTKDAT+3)/4 Size of track
                                            data in words DVTRTRAK And
                                            DVTFTKEY must be grouped together
    0014   20 Signed       4 DVTRTRAK       Relative track for this TCHBK
    0018   24 Signed       4 DVTFTKEY       Key for this TCHBK DVTRTRAK And
                                            DVTFTKEY must be grouped together
    001C   28 Bitstring    1 DVTFLAG        Processing bits
              1... ....      DVTDEL         X'80' DVTDEL Must delete this
                                            TCHBK on back end
              .1.. ....      DVTWFAIL       X'40' DVTWFAIL Write to cache not
                                            performed because track didn't
                                            exist
              ..1. ....      DVTRDF         X'20' DVTRDF Regular data format
    001D   29 Bitstring    3 *              Reserved for IBM use
    0020   32 Signed       4 *              Reserved for IBM use
    0024   36 Signed       4 *              Reserved for IBM use
    0028   40 Dbl-Word     8 * (0)          Must always be DWRD aligned
              00000028       DVTRKLEN       *-DVTRK Header size

#### DVTRK Storage Layout

    *** DVTRK - DASD Virtual TRacK list node
    *
    *     +---------------------------+---------------------------+
    *   0 |         DVTFORW           |         DVTTCHBK          |
    *     +---------------------------+---------------------------+
    *   8 |         DVTCOUNT          |         DVTCDATA          |
    *     +------+------+-------------+---------------------------+
    *  10 |:FILL |:HIRN |/////////////|         DVTRTRAK          |
    *     +------+------+-------------+------+--------------------+
    *  18 |         DVTFTKEY          |:FLAG |////////////////////|
    *     +---------------------------+------+--------------------+
    *  20 |///////////////////////////|///////////////////////////|
    *     +---------------------------+---------------------------+
    *  28
    *
    *** DVTRK - DASD Virtual TRacK list node

#### DVTRK Cross Reference

    Symbol         Dspl Value
    -------------- ---- -----
    DVTCDATA       000C
    DVTCOUNT       0008
    DVTDEL         001C 80
    DVTDPSTF       0011
    DVTFILL        0010
    DVTFLAG        001C
    DVTFORW        0000
    DVTFTKEY       0018
    DVTHIRN        0011
    DVTRDF         001C 20
    DVTRKLEN       0028 00000028
    DVTRTRAK       0014
    DVTTCHBK       0004
    DVTTKDAT       000C
    DVTTKLEN       0012 00000002
    DVTWFAIL       001C 40

This information is based on z/VM V6R1.0. Last updated on 18 Feb 2010 at 08:36:55 EDT.
Copyright IBM Corporation, 1990, 2008