DVTRK Back to Index page
 
Prolog 
Control Block Contents 
   DVTRK DSECT
Storage Layout 
Cross Reference (Contains links to field and bit definitions)
Programming Interface Information:
This information is NOT intended to be
used as Programming Interfaces of z/VM.


  DVTRK Prolog Top of page
 
 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).
 RELOCATION CONSIDERATIONS : None
 COMMENTS   : None
 
 
  DVTRK Control Block Content Top of page
 

 DVTRK DSECT Top of page
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 Top of page
 
          
*** 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 Top of page
 
 
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 7.3.0 Last updated on 22 Jun 2022 at 15:50:04 EDT.
Copyright IBM Corporation, 1990, 2022