DCHSECT

Prolog  

Control Block Contents  
   DCHSECT DSECT

Storage Layout  

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          |///////////////////////////|
*     +---------------------------+---------------------------+
*
*** 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

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