Programming Interface Information:
This information is NOT intended to be
used as Programming Interfaces of z/VM.

SUBBK

Prolog  

Control Block Contents  
   SUBBK DSECT

Storage Layout  

Cross Reference (Contains links to field and bit definitions)  


SUBBK Prolog

 Name       : HCPSUBBK
 Description: Subpool Data Area Block
 DSECT      : SUBBK
 Function   :
              Maps each of the free storage subpool data area
              elements.
 Created by : Never allocated
 Deleted by : Never deallocated
 Notes      : This DSECT is used to map the free storage subpool
              data area groups located in HCPRSM, specifically,
              HCPRSMSS (regular free storage subpools).
              Each data area group consists of multiple data
              area elements.

 

SUBBK Control Block Content


SUBBK DSECT

Hex   Dec Type/Val   Lng Label (dup)    Comments
---- ---- --------- ---- -------------- --------
0000    0 Structure      SUBBK          Subpool Data Area Block
      Format 0 ("old style") SUBBK format used for subpools for
      the following types of subpooled free storage:
      - Virtual Free Storage (HCPVFM)
      - Host Logical Aligned Free Storage (HCPAFS)
      - Verifiable Free Storage (HCPVCB)
0000    0 Signed       4 SUBLOCK        Subpool lock word
0004    4 Signed       4 SUBSIZE        Integral size (in DWDS) of
                                        subpool block including FRERECL
0008    8 Address      8 SUBANCHG       Pointer to 1st SXSTE for
                                        subpooled free storage.
0010   16 Signed       4 SUBODWD        Count of DWD currently in use
                                        (multiple of SUBSIZE)
0014   20 Signed       4 SUBCDWD        Count of DWDS now on chain
0018   24 Signed       4 SUBUDWD        Count of actual DWD usage (does
                                        not include internal
                                        fragmentation)
001C   28 Signed       4 SUBRCNT        Count of requests this size
0020   32 Signed       4 *              Reserved for IBM use
0024   36 Signed       4 *              Reserved for IBM use
0028   40 Signed       4 *              Reserved for IBM use
002C   44 Signed       4 *              Keep total length in whole
                                        numbers of dwords
          00000030       SUBESZ         *-SUBBK Size of one subpool entry
      Format 1 ("new/fast style") SUBBK format used for standard
      short term free storage, including "fast allocated" free
      storage control blocks.
0000    0 Bitstring    1 SUBTSLK        Subpool lock byte
0001    1 Bitstring    1 *              Reserved for IBM use
0002    2 Signed       2 SUBBSIZE       Size in bytes (including
                                        header/trailer) of each block on
                                        this subpool
0004    4 Signed       2 SUBMAXBS       Maximum number of blocks that fit
                                        in one page
0006    6 Signed       2 SUBMTFCT       Count of pages on SUBMTFTE empty
                                        page queue for this subpool Notes
                                        : The following three fields
                                        (SUBFRETS, SUBBLOCK, and
                                        SUBTOTRQ) must remain contiguous
                                        and in order, as there is
                                        performance sensitive code in the
                                        free storage allocation and
                                        deallocation paths which
                                        references two adjacent fields
                                        (SUBBLOCK and SUBTOTRQ for
                                        allocation, SUBFRETS and SUBBLOCK
                                        for deallocation) with a single
                                        STM instruction
0008    8 Signed       4 SUBFRETS       Total count of returns to this
                                        free storage subpool
000C   12 Signed       4 SUBBLOCK       Anchor for blocks on this subpool
0010   16 Signed       4 SUBTOTRQ       Total count of requests against
                                        this subpool
0014   20 Signed       4 SUBCLCTP       Collection pile
0018   24 Address      8 SUBMTFTEG      SXSTE address of 1st empty page
                                        on queue. FFS mark end of chain.
0020   32 Signed       4 SUBXTNCT       Count of extends
0024   36 Signed       4 SUBPAGCT       Count of pages on pool
0028   40 Signed       4 SUBINUSE       Count of blocks in use on this
                                        subpool
002C   44 Signed       4 *              Keep total length in whole
                                        numbers of dwords
          00000030       SUBNEXT        * Address of next SUBBK
          00000030       SUBSSZ         *-SUBBK Size of one standard
                                        short term free storage SUBBK
                                        entry
          00000002       SUBOFFSH       2 Number of bits to shift a
                                        subpool number to get the index
                                        into the HCPFRESO SUBBK offsets
                                        table for the subpool's SUBBK
      Format 2 SUBBK format used for real aligned free storage
0000    0 Signed       4 SUB2LOCK       Subpool lock word
0004    4 Signed       4 SUB2SIZE       Integral size (in DWDS) of
                                        subpool block including FRERECL
0008    8 Address      8 SUB2ANCH       Pointer to 1st FRMTE for
                                        subpooled free storage.
0010   16 Dbl-Word     8 SUB2ODWD       Count of DWD currently in use
                                        (multiple of SUBSIZE)
0018   24 Dbl-Word     8 SUB2CDWD       Count of DWDS now on chain
0020   32 Dbl-Word     8 SUB2UDWD       Count of actual DWD usage (does
                                        not include internal
                                        fragmentation)
0028   40 Signed       4 SUB2RCNT       Count of requests this size
002C   44 Signed       4 *              Keep total length in whole
                                        numbers of dwords
          00000030       SUBASZ         *-SUBBK Size of one subpool entry

 

SUBBK Storage Layout

          
*** SUBBK - Subpool Data Area Block
*
*     +---------------------------+---------------------------+
*   0 |         SUBLOCK           |         SUBSIZE           |
*     +---------------------------+---------------------------+
*   8 |                       SUBANCHG                        |
*     +---------------------------+---------------------------+
*  10 |         SUBODWD           |         SUBCDWD           |
*     +---------------------------+---------------------------+
*  18 |         SUBUDWD           |         SUBRCNT           |
*     +---------------------------+---------------------------+
*  20 |///////////////////////////|///////////////////////////|
*     +---------------------------+---------------------------+
*  28 |///////////////////////////|///////////////////////////|
*     +---------------------------+---------------------------+
*  30
*
*** SUBBK - Subpool Data Area Block
          
*** Overlay for SUBLOCK in SUBBK
*
*     +------+------+-------------+-------------+-------------+
*   0 |:TSLK |//////|  SUBBSIZE   |  SUBMAXBS   |  SUBMTFCT   |
*     +------+------+-------------+-------------+-------------+
*   8 |         SUBFRETS          |         SUBBLOCK          |
*     +---------------------------+---------------------------+
*  10 |         SUBTOTRQ          |         SUBCLCTP          |
*     +---------------------------+---------------------------+
*  18 |                      SUBMTFTEG                        |
*     +---------------------------+---------------------------+
*  20 |         SUBXTNCT          |         SUBPAGCT          |
*     +---------------------------+---------------------------+
*  28 |         SUBINUSE          |///////////////////////////|
*     +---------------------------+---------------------------+
*  30
*
*** Overlay for SUBLOCK in SUBBK
          
*** Overlay for SUBLOCK in SUBBK
*
*     +---------------------------+---------------------------+
*   0 |         SUB2LOCK          |         SUB2SIZE          |
*     +---------------------------+---------------------------+
*   8 |                       SUB2ANCH                        |
*     +-------------------------------------------------------+
*  10 |                       SUB2ODWD                        |
*     +-------------------------------------------------------+
*  18 |                       SUB2CDWD                        |
*     +-------------------------------------------------------+
*  20 |                       SUB2UDWD                        |
*     +---------------------------+---------------------------+
*  28 |         SUB2RCNT          |///////////////////////////|
*     +---------------------------+---------------------------+
*  30
*
*** Overlay for SUBLOCK in SUBBK

 

SUBBK Cross Reference

Symbol         Dspl Value
-------------- ---- -----
SUBANCHG       0008
SUBASZ         002C 00000030
SUBBLOCK       000C
SUBBSIZE       0002
SUBCDWD        0014
SUBCLCTP       0014
SUBESZ         002C 00000030
SUBFRETS       0008
SUBINUSE       0028
SUBLOCK        0000
SUBMAXBS       0004
SUBMTFCT       0006
SUBMTFTEG      0018
SUBNEXT        002C 00000030
SUBODWD        0010
SUBOFFSH       002C 00000002
SUBPAGCT       0024
SUBRCNT        001C
SUBSIZE        0004
SUBSSZ         002C 00000030
SUBTOTRQ       0010
SUBTSLK        0000
SUBUDWD        0018
SUBXTNCT       0020
SUB2ANCH       0008
SUB2CDWD       0018
SUB2LOCK       0000
SUB2ODWD       0010
SUB2RCNT       0028
SUB2SIZE       0004
SUB2UDWD       0020

This information is based on z/VM V5R2.0. Last updated on 12 Apr 2006 at 17:29:14 EDT.
Copyright IBM Corporation, 1990, 2005