STOBK

Prolog  

Control Block Contents  
   STOBK DSECT

Storage Layout  

Cross Reference (Contains links to field and bit definitions)  

STOBK Prolog

 Name       : DMSSTOBK
 Description: Storage descriptor block
 DSECT      : STOBK
 Function   : Mapping macro which maps allocated
              and unallocated storage. There is a STOBK for
              every page of storage within the virtual
              machine.

STOBK Control Block Content

STOBK DSECT

Hex   Dec Type/Val   Lng Label (dup)    Comments
---- ---- --------- ---- -------------- --------
0000    0 Structure      STOBK          Storage descriptor block
0000    0 Signed       4 STOFORWD       Forward pointer for chaining
                                        STOBKs
0004    4 Signed       4 STOBACKW       Backward pointer for chaining
                                        STOBKs
     NOTES : STOKEY and STOFLAG are often moved as a pair. This means that
     they must NEVER be seperated.
0008    8 Signed       2 STOKFMOV (0)   For combined move of STOKEY and
                                        STOFLAG
0008    8 Bitstring    1 STOKEY         Storage key for the described
                                        page
0009    9 Bitstring    1 STOFLAG        Flags to define the described
                                        page
          1... ....      STOPAGE1       X'80' First STOBK on a block of
                                        STOBKs
          .1.. ....      STOBLOK1       X'40' First STOBK anchored on a
                                        SUBBK chain
          ...1 ....      STOFLPT        X'10' Page is a full-partial
                                        (only valid when STOPART flag is
                                        on)
          .... 1...      STORELPG       X'08' Page has not been released
                                        to CP via DIAG X'10'
          .... .1..      STOINTRN       X'04' Page is internal CMS
                                        Storage
          .... ..1.      STOFULL        X'02' Page is fully allocated
          .... ...1      STOPART        X'01' Page is partially allocated
000A   10 Signed       2 STOLARGE       Size of the largest free piece in
                                        a page
000C   12 Signed       4 STOFREEB (0)   Anchor to the free pieces in a
                                        page
000C   12 Signed       4 STOFIRST (0)   Pointer to the first STOBK on a
                                        block
000C   12 Signed       4 STONUMBL       Number of pages on a block
0010   16 Signed       4 STOSUBAD       Pointer to the SUBBK for this
                                        STOBK
0014   20 Signed       4 *              IBM Reserved
          00000018       STOSIZEB       *-STOBK Size of a STOBK in bytes
          00000003       STOSIZED       (STOSIZEB+7)/8 Size of a STOBK in
                                        D-words

STOBK Storage Layout

          
*** STOBK - Storage descriptor block
*
*     +---------------------------+---------------------------+
*   0 |         STOFORWD          |         STOBACKW          |
*     +------+------+-------------+---------------------------+
*   8 |STOKEY|:FLAG |  STOLARGE   |         STONUMBL          |
*     +------+------+-------------+---------------------------+
*  10 |         STOSUBAD          |///////////////////////////|
*     +---------------------------+---------------------------+
*  18
*
*** STOBK - Storage descriptor block

STOBK Cross Reference

Symbol         Dspl Value
-------------- ---- -----
STOBACKW       0004
STOBLOK1       0009 40
STOFIRST       000C
STOFLAG        0009
STOFLPT        0009 10
STOFORWD       0000
STOFREEB       000C
STOFULL        0009 02
STOINTRN       0009 04
STOKEY         0008
STOKFMOV       0008
STOLARGE       000A
STONUMBL       000C
STOPAGE1       0009 80
STOPART        0009 01
STORELPG       0009 08
STOSIZEB       0014 00000018
STOSIZED       0014 00000003
STOSUBAD       0010