SUBBK Back to Index page
 
Prolog 
Control Block Contents 
   SUBBK 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.


  SUBBK Prolog Top of page
  
 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
 RELOCATION CONSIDERATIONS : None
 NOTES      : This DSECT is used to map the free storage subpool
              data structures. These structures are located in
              HCPRSM for all types of free storage except virtual
              free.  Virtual free storage SUBBKs are built in the
              virtual free address space starting at X'800'.
              Each data area group consists of multiple data
              area elements.
              The SUBBKs for all types of free storage except
              for virtual free are a cache line in size. HCPPOOLS
              and HCPRSM ensure cache alignment. This is to avoid
              cache contention between different processors
              allocating blocks from different subpools.
              The SUBBKs for virtual free are not cache aligned.
 
 
  SUBBK Control Block Content Top of page
  




 SUBBK DSECT
Top of page


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 *              Reserved for IBM use
0030   48 Signed       4 *              Reserved for IBM use
0034   52 Signed       4 *              Keep total length in whole
                                        numbers of dwords
          00000038       SUBVSZ         *-SUBBK Virtual free subbk size
0038   56 Dbl-Word     8 * (25)         Reserved for IBM use.
          00000100       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 *              Reserved for IBM use
      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 SUBMTFCT       Count of pages on SUBMTFTE empty
                                        page queue for this subpool
0030   48 Signed       4 SUBBLKCT       Total count of available blocks
                                        on SUBBLOCK queue + the SUBCLCTP
                                        (collection pile) queue. RAS
                                        count maintained only in debug
                                        mode. Combined count enables
                                        accuracy during HCPFRFDX
                                        processing which requeues the
                                        blocks.
0034   52 Signed       4 SUBANYB2G      Count of <2G pages on this
                                        subpool obtained by the SXS page
                                        mgr as a result of an ANY
                                        request. Does not include
                                        disextend queue pages
0038   56 Dbl-Word     8 * (25)         Reserved for IBM use.
          00000100       SUBNEXT        * Address of next SUBBK
          00000100       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 *              Reserved for IBM use
0030   48 Signed       4 *              Reserved for IBM use
0034   52 Signed       4 *              Keep total length in whole
                                        numbers of dwords
0038   56 Dbl-Word     8 * (25)         Reserved for IBM use.
          00000100       SUBASZ         *-SUBBK Size of one subpool entry
 
 
  SUBBK Storage Layout Top of page
  
          
*** SUBBK - Subpool Data Area Block
*
*     +---------------------------+---------------------------+
*   0 |         SUBLOCK           |         SUBSIZE           |
*     +---------------------------+---------------------------+
*   8 |                       SUBANCHG                        |
*     +---------------------------+---------------------------+
*  10 |         SUBODWD           |         SUBCDWD           |
*     +---------------------------+---------------------------+
*  18 |         SUBUDWD           |         SUBRCNT           |
*     +---------------------------+---------------------------+
*  20 |///////////////////////////|///////////////////////////|
*     +---------------------------+---------------------------+
*  28 |///////////////////////////|///////////////////////////|
*     +---------------------------+---------------------------+
*  30 |///////////////////////////|///////////////////////////|
*     +---------------------------+---------------------------+
*  38 |///////////////////////////////////////////////////////|
*     =///////////////////////////////////////////////////////=
*     |///////////////////////////////////////////////////////|
*     +-------------------------------------------------------+
* 100
*
*** SUBBK - Subpool Data Area Block
          
*** Overlay for SUBLOCK in SUBBK
*
*     +------+------+-------------+-------------+-------------+
*   0 |:TSLK |//////|  SUBBSIZE   |  SUBMAXBS   |/////////////|
*     +------+------+-------------+-------------+-------------+
*   8 |         SUBFRETS          |         SUBBLOCK          |
*     +---------------------------+---------------------------+
*  10 |         SUBTOTRQ          |         SUBCLCTP          |
*     +---------------------------+---------------------------+
*  18 |                      SUBMTFTEG                        |
*     +---------------------------+---------------------------+
*  20 |         SUBXTNCT          |         SUBPAGCT          |
*     +---------------------------+---------------------------+
*  28 |         SUBINUSE          |         SUBMTFCT          |
*     +---------------------------+---------------------------+
*  30 |         SUBBLKCT          |        SUBANYB2G          |
*     +---------------------------+---------------------------+
*  38 |///////////////////////////////////////////////////////|
*     =///////////////////////////////////////////////////////=
*     |///////////////////////////////////////////////////////|
*     +-------------------------------------------------------+
* 100
*
*** Overlay for SUBLOCK in SUBBK
          
*** Overlay for SUBLOCK in SUBBK
*
*     +---------------------------+---------------------------+
*   0 |         SUB2LOCK          |         SUB2SIZE          |
*     +---------------------------+---------------------------+
*   8 |                       SUB2ANCH                        |
*     +-------------------------------------------------------+
*  10 |                       SUB2ODWD                        |
*     +-------------------------------------------------------+
*  18 |                       SUB2CDWD                        |
*     +-------------------------------------------------------+
*  20 |                       SUB2UDWD                        |
*     +---------------------------+---------------------------+
*  28 |         SUB2RCNT          |///////////////////////////|
*     +---------------------------+---------------------------+
*  30 |///////////////////////////|///////////////////////////|
*     +---------------------------+---------------------------+
*  38 |///////////////////////////////////////////////////////|
*     =///////////////////////////////////////////////////////=
*     |///////////////////////////////////////////////////////|
*     +-------------------------------------------------------+
* 100
*
*** Overlay for SUBLOCK in SUBBK
 
 
  SUBBK Cross Reference Top of page
  
 
Symbol         Dspl Value
-------------- ---- -----
SUBANCHG       0008
SUBANYB2G      0034
SUBASZ         0038 00000100
SUBBLKCT       0030
SUBBLOCK       000C
SUBBSIZE       0002
SUBCDWD        0014
SUBCLCTP       0014
SUBESZ         0038 00000100
SUBFRETS       0008
SUBINUSE       0028
SUBLOCK        0000
SUBMAXBS       0004
SUBMTFCT       002C
SUBMTFTEG      0018
SUBNEXT        0038 00000100
SUBODWD        0010
SUBOFFSH       0038 00000002
SUBPAGCT       0024
SUBRCNT        001C
SUBSIZE        0004
SUBSSZ         0038 00000100
SUBTOTRQ       0010
SUBTSLK        0000
SUBUDWD        0018
SUBVSZ         0034 00000038
SUBXTNCT       0020
SUB2ANCH       0008
SUB2CDWD       0018
SUB2LOCK       0000
SUB2ODWD       0010
SUB2RCNT       0028
SUB2SIZE       0004
SUB2UDWD       0020
 
This information is based on z/VM 7.4.0 Last updated on 24 Jun 2024 at 11:34:27 EDT.
Copyright IBM Corporation, 1990, 2024