ACABK Back to Index page
 
Prolog 
Control Block Contents 
   ACABK 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.


  ACABK Prolog Top of page
 
 NAME       : HCPVEXBK
 DESCRIPTION: Map CASBKs at beginning of VEXBK.
 DSECT      : ACABK
 NOTES      : The following maps the area at the beginning of the
              VEXBK which contains the CASBKs.  Hence, this DSECT
              is called the ACABK (Area for Contiguous Available
              Slots).  The ACABK is used to avoid checking for
              page or spool slots numerous times.
 
 
  ACABK Control Block Content Top of page
 

 ACABK DSECT Top of page
Hex Dec Type/Val Lng Label (dup) Comments ---- ---- --------- ---- -------------- -------- 0000 0 Structure ACABK Map CASBKs at beginning of VEXBK. 0000 0 Signed 4 ACACAS (16) Contains 16 CASBKS used by slot allocation. 0040 64 Signed 4 ACACURSL Current slot number in EXTBK (start search for new CASBK here) 0044 68 Signed 4 ACALSTSL Last slot in current cylinder 0048 72 Signed 4 ACACURCY Current cylinder in EXTBK 004C 76 Signed 4 ACAEXTBK Pointer to current EXTBK 0050 80 Bitstring 1 ACAFIRST Index into ACABK of first CASBK 0051 81 Bitstring 1 ACALAST Index into ACABK of last CASBK 0052 82 Bitstring 1 ACAFLAG Flags 1... .... ACAREDO X'80' ACAREDO Slots were allocated by a method other than slot alloc. (PGC or PGTDA) Redo CASBKs before slot allocation. .1.. .... ACAANYRP X'40' ACAANYRP No minimum size when searching for a replacement CASBK. (space is fragmented) ..1. .... ACAANYAL X'20' ACAANYAL Take any size CASBK when searching for a block for allocation. (this is set temporarily for large block requests) ...1 .... ACAINIT X'10' ACAINIT CASBKs have been initialized 0053 83 Bitstring 1 * (5) Reserved for IBM use 00000058 ACASIZE *-ACABK Size of area for CASBKs.
 
 
  ACABK Storage Layout Top of page
 
          
*** ACABK - Map CASBKs at beginning of VEXBK.
*
*     +-------------------------------------------------------+
*   0 |                                                       |
*     =                        ACACAS                         =
*     |                                                       |
*     +---------------------------+---------------------------+
*  40 |         ACACURSL          |         ACALSTSL          |
*     +---------------------------+---------------------------+
*  48 |         ACACURCY          |         ACAEXTBK          |
*     +------+------+------+------+---------------------------+
*  50 |:FIRST|:LAST |:FLAG |//////////////////////////////////|
*     +------+------+------+----------------------------------+
*  58
*
*** ACABK - Map CASBKs at beginning of VEXBK.
 
 
  ACABK Cross Reference Top of page
 
 
Symbol         Dspl Value
-------------- ---- -----
ACAANYAL       0052 20
ACAANYRP       0052 40
ACACAS         0000
ACACURCY       0048
ACACURSL       0040
ACAEXTBK       004C
ACAFIRST       0050
ACAFLAG        0052
ACAINIT        0052 10
ACALAST        0051
ACALSTSL       0044
ACAREDO        0052 80
ACASIZE        0053 00000058
 
This information is based on z/VM 7.3.0 Last updated on 22 Jun 2022 at 15:57:41 EDT.
Copyright IBM Corporation, 1990, 2022