QDGBL Back to Index page
 
Prolog 
Control Block Contents 
   QDGBL 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.


  QDGBL Prolog Top of page
 
 NAME       : Virtual Disk in Storage Global Control Block
 DESCRIPTION: V-Disk Global Control Block
 DSECT      : QDGBL
 FUNCTION   : This control block maps the global V-Disk
              control block for the system.
 LOCATED BY : HCPSYSCM - System Common Area
 CREATED BY : HCPQDLIN
 DELETED BY : none
 SERIALIZED : QDGALOCK is used to serialize the QDGBL control block
              fields.  QDGCLOCK is used to serialize the VDISK MDISK
              chain (located by QDGMDISK).  Either QDGALOCK or
              QDGCLOCK should be held shared when looking at the
              VDISK MDISK chain.  Both must be held exclusive when
              changing the VDISK MDISK chain.
 RELOCATION CONSIDERATIONS : None
 
 
  QDGBL Control Block Content Top of page
 

 QDGBL DSECT Top of page
Hex Dec Type/Val Lng Label (dup) Comments ---- ---- --------- ---- -------------- -------- 0000 0 Structure QDGBL V-Disk Global Control Block Vdisk chain of MDISK blocks and allocation lockword 0000 0 Dbl-Word 8 QDGALOCK (3) Vdisk Allocation Lockword 0018 24 Dbl-Word 8 QDGCLOCK (3) Vdisk MDISK chain lock 0030 48 Signed 4 QDGMDISK First MDISK block for Vdisk Fields for keeping track of limits (in blocks) 0034 52 Signed 4 QDGSYSLM Limit of total Vdisk allocation 0038 56 Signed 4 QDGUSRLM Limit of size of Vdisks DEFINEd by a user (using DEFINE) 003C 60 Signed 4 QDGSYSCA Total currently-allocated Vdisk blocks 0040 64 Signed 4 QDGRELOC Total relocation-allocated VDISK blocks 0044 68 Signed 2 * Reserved 0046 70 Signed 2 QDGCOUNT Vdisk counter for addr. space name (increment and save) 0048 72 Signed 4 QDGLKCNT Total number of LINKs to all Vdisks (includes 1 for each DEFINEd VDisk) 004C 76 Signed 4 QDGDISKS Total number of existing Vdisks 0050 80 Signed 4 QDGSYSLD Default of QDGSYSLM 0054 84 Signed 4 QDGUSRLD Default of QDGUSRLM 0058 88 Bitstring 1 QDGAFLAG 'A' flag byte 1... .... QDGASYSC X'80' QDGASYSC - SYSTEM CONFIG set syslim 0059 89 Bitstring 1 * (3) Reserved 0000000C QDGSIZE ((*-QDGBL+7)/8) SIZE IN DWS FOR FREE/FRET
 
 
  QDGBL Storage Layout Top of page
 
 
*** QDGBL - V-Disk Global Control Block
*
*     +-------------------------------------------------------+
*   0 |                                                       |
*     =                       QDGALOCK                        =
*     |                                                       |
*     +-------------------------------------------------------+
*  18 |                                                       |
*     =                       QDGCLOCK                        =
*     |                                                       |
*     +---------------------------+---------------------------+
*  30 |         QDGMDISK          |         QDGSYSLM          |
*     +---------------------------+---------------------------+
*  38 |         QDGUSRLM          |         QDGSYSCA          |
*     +---------------------------+-------------+-------------+
*  40 |         QDGRELOC          |/////////////|  QDGCOUNT   |
*     +---------------------------+-------------+-------------+
*  48 |         QDGLKCNT          |         QDGDISKS          |
*     +---------------------------+---------------------------+
*  50 |         QDGSYSLD          |         QDGUSRLD          |
*     +------+--------------------+---------------------------+
*  58 |:AFLAG|////////////////////| 5C
*     +------+--------------------+
*
*** QDGBL - V-Disk Global Control Block
 
 
  QDGBL Cross Reference Top of page
 
 
Symbol         Dspl Value
-------------- ---- -----
QDGAFLAG       0058
QDGALOCK       0000
QDGASYSC       0058 80
QDGCLOCK       0018
QDGCOUNT       0046
QDGDISKS       004C
QDGLKCNT       0048
QDGMDISK       0030
QDGRELOC       0040
QDGSIZE        0059 0000000C
QDGSYSCA       003C
QDGSYSLD       0050
QDGSYSLM       0034
QDGUSRLD       0054
QDGUSRLM       0038
 
This information is based on z/VM 6.4.0 Last updated on 24 Aug 2016 at 09:42:28 EDT.
Copyright IBM Corporation, 1990, 2016