Programming Interface Information:
This information is NOT intended to be
used as Programming Interfaces of z/VM. |
DVTRK
Control Block Contents
DVTRK DSECT
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' Must delete this TCHBK on back end .1.. .... DVTWFAIL X'40' Write to cache not performed because track didn't exist ..1. .... DVTRDF X'20' 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
Last updated on 5 Jun 2001 at 13:30:16 EDT.
Copyright IBM Corporation, 1990, 2001