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Programming Interface Information:
This information is NOT
intended to be
used as Programming Interfaces of VM/ESA. It is to be used for diagnosis only. |
DCHSECT
Cross Reference (Contains links to field and bit definitions)
DCHSECT Prolog
Name : DCH Description: Data Control Hyperblock DSECT : DCHSECT Notes : MODULE TYPE - Macro Function : This is the bilingual macro containing the mapping of the data control hyperblock, used to contain cached or accessed FSTs for both SFS directories and CMS formatted minidisks.
DCHSECT Control Block Content
DCHSECT DSECT
Hex Dec Type/Val Lng Label (dup) Comments ---- ---- --------- ---- -------------- -------- 0000 0 Structure DCHSECT Data Control Hyperblock 0000 0 Address 4 DCHFWPTR FORWARD POINTER 0004 4 Address 4 DCHBWPTR BACKWARD POINTER 0008 8 Signed 4 DCHDWSIZ FULL HYPERBLK STOR SIZE IN DWORDS 000C 12 Address 4 DCHTRUNK ADDR OF NEXT BLK UP IN STRUCTURE 000C 12 Signed 4 DCHFSTIU Count of used FSTs in Caching HB 0010 16 Signed 4 DCHTDISP DISP TO DISK ADR IN TRUNK PTR BLK 0010 16 Address 4 DCHDSPTR Address of data space hyperblock 0014 20 Signed 4 DCHDTSIZ DATA PORTION SIZE IN BYTES 0018 24 Signed 4 DCHSEQBD SEQUENTIAL DATA BLK DISPLACEMENT 001C 28 Bitstring 1 DCHFLG1 DCH FLAG 1 ** EQUATES FOR DCHFLG1 1... .... DCHCHOP X'80' DEALLOC THIS DIR. BLK. DURING DIRECTORY UPDATE .1.. .... DCHNEW X'40' DO NOT REALLOC THIS DIR. BLK. DURING DIRECTORY UPDATE ..1. .... DCHDALLO X'20' DISK ADDRESS OF BLOCK IS IN DE-ALLOCATION LIST ...1 .... DCHCHGD X'10' BLOCK HAS BEEN ALTERED .... 1... DCHRALLO X'08' DISK ADDRESS OF BLOCK IS IN RE-ALLOCATION LIST .... .1.. DCHAUX X'04' AUX DIR HAS BEEN CREATED 001D 29 Bitstring 1 DCHFLG2 DCH FLAG 2 ** EQUATES FOR DCHFLG2 1... .... DCHFULL X'80' ALL DSK BLKS ALLOC'D IN THIS HBLK .1.. .... DCHDA X'40' ALL DSK BLKS DEALLOCATED BY ERS ..1. .... DCHLHBLK X'20' LAST HBLK IN BUFFER CH FOR ERS ...1 .... DCHDUM X'10' DUMMY HBLK FOR CHAINING AUX DIR .... 1... DCHSHR X'08' BLK IS IN SHARED STORAGE 001E 30 Bitstring 1 DCHFLG3 DCH FLAG 3 - RESERVED - 001F 31 Bitstring 1 DCHFLG4 DCH FLAG 4 - RESERVED - 2 Fields used only for alloc map 0020 32 Signed 4 DCHDAMAP DEALLOCATION MAP ADDRESS 0024 36 Signed 4 DCHCHMAP CHANGE MAP ADDRESS 0020 32 Signed 4 DCHYDISP Pointer block displacement used by DMSERC for file truncation. 0024 36 Signed 4 DCHCOUNT Data block count used (lvl 1 only) by DMSERC for file truncation. 0020 32 Signed 4 DCHOFFST Offset into data block by DMSERC for file truncation. 0024 36 Signed 4 DCHLSTRC Last record in V-file used by DMSERC for file truncation. 0028 40 Signed 4 DCHBUFAD Hyperblock buffer address for read/only Stat minidisks. 002C 44 Signed 4 * reserved 0030 48 Dbl-Word 8 * (0) 00000030 DCHPFIXL *-DCHSECT LENGTH OF PREFIX PORTION OF HBLK 0030 48 Dbl-Word 8 DCHDATA (0)
DCHSECT Storage Layout
*** DCHSECT - Data Control Hyperblock * * +---------------------------+---------------------------+ * 0 | DCHFWPTR | DCHBWPTR | * +---------------------------+---------------------------+ * 8 | DCHDWSIZ | DCHTRUNK | * +---------------------------+---------------------------+ * 10 | DCHTDISP | DCHDTSIZ | * +---------------------------+------+------+------+------+ * 18 | DCHSEQBD |:FLG1 |:FLG2 |:FLG3 |:FLG4 | * +---------------------------+------+------+------+------+ * 20 | DCHDAMAP | DCHCHMAP | * +---------------------------+---------------------------+ * 28 | DCHBUFAD |///////////////////////////| * +---------------------------+---------------------------+ * 30 | | * = DCHDATA = * | | * +-------------------------------------------------------+ * *** DCHSECT - Data Control Hyperblock *** Overlay for DCHTRUNK in DCHSECT * * +---------------------------+ * 8 ... C | DCHFSTIU | * +---------------------------+ * 10 * *** Overlay for DCHTRUNK in DCHSECT *** Overlay for DCHTDISP in DCHSECT * * +---------------------------+ * 10 | DCHDSPTR | 14 * +---------------------------+ * *** Overlay for DCHTDISP in DCHSECT *** Overlay for DCHDAMAP in DCHSECT * * +---------------------------+---------------------------+ * 20 | DCHYDISP | DCHCOUNT | * +---------------------------+---------------------------+ * 28 * *** Overlay for DCHDAMAP in DCHSECT *** Overlay for DCHDAMAP in DCHSECT * * +---------------------------+---------------------------+ * 20 | DCHOFFST | DCHLSTRC | * +---------------------------+---------------------------+ * 28 * *** Overlay for DCHDAMAP in DCHSECT
DCHSECT Cross Reference
(contains links to field and bit definitions)Symbol Dspl Value -------------- ---- -----DCHAUX 001C 04
DCHBUFAD 0028
DCHBWPTR 0004
DCHCHGD 001C 10
DCHCHMAP 0024
DCHCHOP 001C 80
DCHCOUNT 0024
DCHDA 001D 40
DCHDALLO 001C 20
DCHDAMAP 0020
DCHDATA 0030
DCHDSPTR 0010
DCHDTSIZ 0014
DCHDUM 001D 10
DCHDWSIZ 0008
DCHFLG1 001C
DCHFLG2 001D
DCHFLG3 001E
DCHFLG4 001F
DCHFSTIU 000C
DCHFULL 001D 80
DCHFWPTR 0000
DCHLHBLK 001D 20
DCHLSTRC 0024
DCHNEW 001C 40
DCHOFFST 0020
DCHPFIXL 0030 00000030
DCHRALLO 001C 08
DCHSEQBD 0018
DCHSHR 001D 08
DCHTDISP 0010
DCHTRUNK 000C
DCHYDISP 0020
Last updated on 12 Aug 1999 at 11:18:47 EDT.
Copyright IBM Corporation, 1990, 1999