VEXBK Back to Index page
 
Prolog 
Control Block Contents 
   VEXBK 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.


  VEXBK Prolog Top of page
 
 NAME       : HCPVEXBK
 DESCRIPTION: Volume EXtent block
 DSECT      : VEXBK
 FUNCTION   : Contains information about all of the extents on a
              CP-owned volume.
 LOCATED BY : CPVVEXBK
 CREATED BY : HCPRDAAT when CP-owned volume attached
              to system
 DELETED BY : HCPRDDDT when CP-owned volume detached
              from system
 REFERENCES : HCPEXTBK - Extent block
 SERIALIZED : Allocation locks
 RELOCATION CONSIDERATIONS : None
 NOTES      : The fields starting at VEXPGACA and VEXSPACA each cannot
              cross a 256-byte boundary because the internal CASBK
              pointers (CASNXT) are one-byte fields.  To guarantee
              these fields do not cross a 256 byte-boundary,
              ALLOC=ALIGNED is specified in IDOFFSET macro AND
              currently the block has a maximum length of 256 bytes.
              The length of 256 bytes PLUS ALLOC=ALIGNED forces the
              control block to be located on a 256-byte boundary.
              If this control block grows larger than 256 bytes,
              then VEXSIZE as well as the locations of VEXPGACA and
              VEXSPACA may need to change.
 
 
  VEXBK Control Block Content Top of page
 

 VEXBK DSECT Top of page
Hex Dec Type/Val Lng Label (dup) Comments ---- ---- --------- ---- -------------- -------- 0000 0 Structure VEXBK Volume EXtent block The following section of the VEXBK contains information regarding the PAGE space on this volume. This information is for page slot allocation. This is the area containing page CASBKs (groups of Contiguous Available Slots) and is mapped by ACABK DSECT (Area for Contiguous Available Slots). 0000 0 Dbl-Word 8 * (0) 0000 0 Signed 4 VEXPGACA (16) Contains 16 CASBKs used by slot allocation. 0040 64 Signed 4 * Current slot number in EXTBK (start search for new CASBK here) 0044 68 Signed 4 * Last slot in current cylinder 0048 72 Signed 4 * Current cylinder in EXTBK 004C 76 Signed 4 * Pointer to current EXTBK 0050 80 Bitstring 1 * Index into ACABK of first CASBK 0051 81 Bitstring 1 * Index into ACABK of last CASBK 0052 82 Bitstring 1 * Flags 0053 83 Bitstring 1 * (5) Reserved for IBM use The following section of the VEXBK contains information regarding the SPOOL space on this volume. This information is for spool slot allocation. This is the area containing page CASBKs (groups of Contiguous Available Slots) and is mapped by ACABK DSECT (Area for Contiguous Available Slots). 0058 88 Dbl-Word 8 * (0) 0058 88 Signed 4 VEXSPACA (16) Contains 16 CASBKs used by slot allocation. 0098 152 Signed 4 * Current slot number in EXTBK (start search for new CASBK here) 009C 156 Signed 4 * Last slot in current cylinder 00A0 160 Signed 4 * Current cylinder in EXTBK 00A4 164 Signed 4 * Pointer to current EXTBK 00A8 168 Bitstring 1 * Index into ACABK of first CASBK 00A9 169 Bitstring 1 * Index into ACABK of last CASBK 00AA 170 Bitstring 1 * Flags 00AB 171 Bitstring 1 * (5) Reserved for IBM use The following section of the VEXBK is a general section containing pointers to the first EXTBK of each type and the number of EXTBKs of each type, as well as descriptions about the device geometry. If one of the following pointers is 0, then no space of that type exists on the volume. 00B0 176 Signed 4 VEXPGEXT Ptr to 1st page EXTBK on volume 00000004 VEXPTRL *-VEXPGEXT Length of each pointer field 00B4 180 Signed 4 VEXSPEXT Ptr to 1st spool EXTBK on volume 00B8 184 Signed 4 VEXTDEXT Ptr to 1st tdsk EXTBK on volume 00BC 188 Signed 4 VEXDREXT Ptr to 1st drct EXTBK on volume 00C0 192 Signed 4 VEXPEEXT Ptr to 1st perm EXTBK on volume 00000014 VEXPTRT *-VEXPGEXT Total area for pointers 00000005 VEXTYP VEXPTRT/VEXPTRL Number of allocation types with EXTBKs 00C4 196 Signed 4 VEX1SEXT Pointer to 1st EXTBK of any type 00C8 200 Signed 2 VEXPGNUM Number page EXTBKs on volume 00000002 VEXCTRL *-VEXPGNUM Length of each counter field 00CA 202 Signed 2 VEXSPNUM Number spool EXTBKs on volume 00CC 204 Signed 2 VEXTDNUM Number tdsk EXTBKs on volume 00CE 206 Signed 2 VEXDRNUM Number drct EXTBKs on volume 00D0 208 Signed 2 VEXPENUM Number perm EXTBKs on volume 00D2 210 Signed 2 VEXNUMEX Total number EXTBKs on volume 00D4 212 Bitstring 1 VEXTYPES Indicates all allocation types that exist on the volume. PARM and UNDF types are marked separately in VEXFLAGS. 1... .... ALOCATED X'80' ALOCATED CYLINDER IS CURRENTLY IN USE THIS TYPE OF ALLOCATION SHOULD ONLY BE USED IN CONJUNCTION WITH THE TYPE 'DRCT' .1.. .... ALOCDRCT X'40' ALOCDRCT ALLOCATION TYPE 'DRCT' ..1. .... ALOCTDSK X'20' ALOCTDSK ALLOCATION TYPE 'TDSK' ...1 .... ALOCFULL X'10' ALOCFULL CYLINDER IS FULL NOTE- ALOCFULL is used only in combination with SPOL & PAGE .... 1... ALOCPERM X'08' ALOCPERM ALLOCATION TYPE 'PERM' .... ..1. ALOCSPOL X'02' ALOCSPOL ALLOCATION TYPE 'SPOL' Notes : ALOCSPOL == PGTSPOOL == PGUSPOOL == CPVTEMPS: 00D5 213 Bitstring 1 VEXAVAIL Indicates which types have available space on the volume. PARM and UNDF types are marked separately in VEXFLAGS. 1... .... ALOCATED X'80' ALOCATED CYLINDER IS CURRENTLY IN USE THIS TYPE OF ALLOCATION SHOULD ONLY BE USED IN CONJUNCTION WITH THE TYPE 'DRCT' .1.. .... ALOCDRCT X'40' ALOCDRCT ALLOCATION TYPE 'DRCT' ..1. .... ALOCTDSK X'20' ALOCTDSK ALLOCATION TYPE 'TDSK' ...1 .... ALOCFULL X'10' ALOCFULL CYLINDER IS FULL NOTE- ALOCFULL is used only in combination with SPOL & PAGE .... 1... ALOCPERM X'08' ALOCPERM ALLOCATION TYPE 'PERM' .... ..1. ALOCSPOL X'02' ALOCSPOL ALLOCATION TYPE 'SPOL' Notes : ALOCSPOL == PGTSPOOL == PGUSPOOL == CPVTEMPS: 00D6 214 Signed 2 VEXPGCYL Pages per cylinder (Valid only for CKD devices) 00D8 216 Bitstring 1 VEXVOL Volume index (v of ccpv) 00D9 217 Bitstring 1 VEXFLAGS Flag byte 1... .... VEXFBA X'80' VEXFBA FBA indicator .1.. .... VEXNFIL X'40' VEXNFIL Device formatted without filler records ..1. .... VEXUNDF X'20' VEXUNDF Device contains undefined allocation types. Those areas will be ignored. ...1 .... VEXPARM X'10' VEXPARM Device contains cyls/pages with PARM allocation type 'Sharable' Extents are: PERM, PARM 'Owner-Shared' Extents are: SPOL 'Private' Extents are: PAGE, TDSK, WARM, CKPT, DRCT 00DA 218 Bitstring 1 VEXFLGS2 Flag byte 1... .... VEXSHROF X'80' VEXSHROF Sharable extents are OFF .1.. .... VEXOSHOF X'40' VEXOSHOF Owner-Shared extents are OFF ..1. .... VEXPRVOF X'20' VEXPRVOF Private extents are OFF 00DB 219 Bitstring 1 * Reserved for IBM use 00DC 220 Signed 4 VEXEND Number of cylinders (CKD) or slots (FBA) on device 00E0 224 Signed 4 VEXMXCYL Maximum number of cylinders per page/spool EXTBK (Used only for CKD device) 00000020 VEXSIZE 256/8 Current maximum size of VEXBK in Dwords. This forces VEXBK to be aligned on a 256-byte boundary.
 
 
  VEXBK Storage Layout Top of page
 
          
*** VEXBK - Volume EXtent block
*
*     +-------------------------------------------------------+
*   0 |                                                       |
*     =                       VEXPGACA                        =
*     |                                                       |
*     +---------------------------+---------------------------+
*  40 |///////////////////////////|///////////////////////////|
*     +---------------------------+---------------------------+
*  48 |///////////////////////////|///////////////////////////|
*     +------+------+------+------+---------------------------+
*  50 |//////|//////|//////|//////////////////////////////////|
*     +------+------+------+----------------------------------+
*  58 |                                                       |
*     =                       VEXSPACA                        =
*     |                                                       |
*     +---------------------------+---------------------------+
*  98 |///////////////////////////|///////////////////////////|
*     +---------------------------+---------------------------+
*  A0 |///////////////////////////|///////////////////////////|
*     +------+------+------+------+---------------------------+
*  A8 |//////|//////|//////|//////////////////////////////////|
*     +------+------+------+------+---------------------------+
*  B0 |         VEXPGEXT          |         VEXSPEXT          |
*     +---------------------------+---------------------------+
*  B8 |         VEXTDEXT          |         VEXDREXT          |
*     +---------------------------+---------------------------+
*  C0 |         VEXPEEXT          |         VEX1SEXT          |
*     +-------------+-------------+-------------+-------------+
*  C8 |  VEXPGNUM   |  VEXSPNUM   |  VEXTDNUM   |  VEXDRNUM   |
*     +-------------+-------------+------+------+-------------+
*  D0 |  VEXPENUM   |  VEXNUMEX   |:TYPES|:AVAIL|  VEXPGCYL   |
*     +------+------+------+------+------+------+-------------+
*  D8 |VEXVOL|:FLAGS|:FLGS2|//////|          VEXEND           |
*     +------+------+------+------+---------------------------+
*  E0 |         VEXMXCYL          | E4
*     +---------------------------+
*
*** VEXBK - Volume EXtent block
 
 
  VEXBK Cross Reference Top of page
 
 
Symbol         Dspl Value
-------------- ---- -----
ALOCATED       00D4 80
ALOCATED       00D5 80
ALOCDRCT       00D4 40
ALOCDRCT       00D5 40
ALOCFULL       00D4 10
ALOCFULL       00D5 10
ALOCPERM       00D4 08
ALOCPERM       00D5 08
ALOCSPOL       00D4 02
ALOCSPOL       00D5 02
ALOCTDSK       00D4 20
ALOCTDSK       00D5 20
VEXAVAIL       00D5
VEXCTRL        00C8 00000002
VEXDREXT       00BC
VEXDRNUM       00CE
VEXEND         00DC
VEXFBA         00D9 80
VEXFLAGS       00D9
VEXFLGS2       00DA
VEXMXCYL       00E0
VEXNFIL        00D9 40
VEXNUMEX       00D2
VEXOSHOF       00DA 40
VEXPARM        00D9 10
VEXPEEXT       00C0
VEXPENUM       00D0
VEXPGACA       0000
VEXPGCYL       00D6
VEXPGEXT       00B0
VEXPGNUM       00C8
VEXPRVOF       00DA 20
VEXPTRL        00B0 00000004
VEXPTRT        00C0 00000014
VEXSHROF       00DA 80
VEXSIZE        00E0 00000020
VEXSPACA       0058
VEXSPEXT       00B4
VEXSPNUM       00CA
VEXTDEXT       00B8
VEXTDNUM       00CC
VEXTYP         00C0 00000005
VEXTYPES       00D4
VEXUNDF        00D9 20
VEXVOL         00D8
VEX1SEXT       00C4
 
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