NAME       : HCPVACBK
 DESCRIPTION: Vacator Block
 DSECT      : VACBK
 FUNCTION   : Represents one Dynamic Memory Downgrade function
 LOCATED BY : RSAVACBK in HCPRSMCM (RSMBK)
 CREATED BY : HCPVAC
 DELETED BY : HCPVAC
 REFERENCES : VMDBK   Virtual Machine Definition block
              VCZBK   Vacator Zone block
              SVGBK   Save Area block
 SERIALIZED : Fields that are filled in during creation of the block do not
              need serialization because only the creator knows about them.
              Fields that are filled in at the end of a DMD do not need
              serialization because only the last outstanding HCPVACBE task
              will be touching them.
              All other fields, which are mainly counts, should be updated
              with CS logic to avoid data loss.  The exception is RAS-only
              fields which may not require the CS logic.
 RELOCATION CONSIDERATIONS : None
 COMPATIBILITY AND MIGRATION CONCERNS : Only those which are common to all control blocks
 NOTES      :

 VACBK DSECT
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Hex   Dec Type/Val   Lng Label (dup)    Comments
---- ---- --------- ---- -------------- --------
0000    0 Structure      VACBK          Vacator Block
0000    0 Signed       4 VACNEXT        Ptr to next VACBK in historical
                                        queue
0004    4 Signed       4 VACTOSSC       Count of time TOSS_VCFBKS was
                                        called during this downgrade
                                        (RAS)
0008    8 Dbl-Word     8 VACSTRTS       Timestamp of start of vacator
0010   16 Dbl-Word     8 VACENDTS       Timestamp of end of vacator
0018   24 Dbl-Word     8 VACTKCPE       CPEBK addr for
                                        HCPPSSCC-maintained count
0018   24 Signed       4 *              VACTKCPE word for CPEBK addr
001C   28 Signed       4 VACTASKS       Zones yet to complete (HCPPSSCC-
                                        maintained)
      Status flags may progress only as follows:
              VACSTATU              VACCOMPF
              ========              ========
                INPRG                  00
                DONE                  SUCC
          or
                INPRG                  00
                ABORT           HALTD, VTCAN, or SZCAN
                DONE            HALTD, VTCAN, or SZCAN
0020   32 Bitstring    1 VACSTATU       Flags for status of memory
                                        downgrade
          1... ....      VACINPRG       X'80' VACINPRG vacate in progress
          .1.. ....      VACABORT       X'40' VACABORT vacate is
                                        halting/cancelling
          ..1. ....      VACDONE        X'20' VACDONE vacate is complete
                                        (success or halted)
          .... .1..      VACPONR        X'04' VACPONR point of no return
                                        reached (no halt)
          .... ..1.      VACVCFTH       X'02' VACVCFTH VCFBK throttle is
                                        in effect
          .... ...1      VACZONFL       X'01' VACZONFL at least one zone
                                        failed and was marked
                                        AvlBeenTried
0021   33 Bitstring    1 *              Reserved for IBM use
0022   34 Bitstring    1 *              Reserved for IBM use
0023   35 Bitstring    1 *              Reserved for IBM use
      Fields governed by VACVCZLK:
0024   36 Signed       4 VACVCZLL       Circular doubly-linked list of
                                        VCZBKs
0028   40 Signed       4 VACVCZCT       Count of VCZBKs in linked list
002C   44 Signed       4 VACRUNCT       Count of active threads (VCZBKs
                                        in linked list marked
                                        "stacked/running", i.e. with
                                        VCZRUNNG set)
0030   48 Signed       4 VACWAICT       Count of waiting threads (VCZBKs
                                        in linked list marked "waiting to
                                        run", i.e. with VCZWAITN set) end
                                        of Fields governed by VACVCZLK
0034   52 Signed       4 VACMXCPU       Max number of threads allowed to
                                        be running at one time
0038   56 Signed       4 VACVCFCT       Count of VCFBKs in existence for
                                        this DMD
003C   60 Signed       4 VACRESUM       Address at which to resume HCPVAC
                                        once all threads are done
0040   64 Signed       4 VACSVGBK       SVGBK addr to resume on
0044   68 Signed       4 VACSKIPS       Times any frame was skipped by
                                        vacator
0048   72 Signed       4 VACVCFMX       Max number of VCFBKs allowed at
                                        any moment
0050   80 Dbl-Word     8 VACORIGF       Original frame count to be
                                        vacated
0058   88 Dbl-Word     8 VACVCZLK (6)   Formal spin lock that governs: -
                                        VACVCZLL, VACVCZCT, VACRUNCT, and
                                        VACWAICT in VACBK - VCZRUNNG,
                                        VCZWAITN, and VCZDONE bits in
                                        VCZSTATF field
          00000011       VACSIZE        (*-VACBK+7)/8 size in double
                                        words
          00000088       VACBSIZE       VACSIZE*8 size in bytes

          
*** VACBK - Vacator Block
*
*     +---------------------------+---------------------------+
*   0 |         VACNEXT           |         VACTOSSC          |
*     +---------------------------+---------------------------+
*   8 |                       VACSTRTS                        |
*     +-------------------------------------------------------+
*  10 |                       VACENDTS                        |
*     +-------------------------------------------------------+
*  18 |                       VACTKCPE                        |
*     +-------------------------------------------------------+
*  20
*
*** VACBK - Vacator Block
          
*** Overlay for VACTKCPE in VACBK
*
*     +---------------------------+---------------------------+
*  18 |///////////////////////////|         VACTASKS          |
*     +------+------+------+------+---------------------------+
*  20 |:STATU|//////|//////|//////|         VACVCZLL          |
*     +------+------+------+------+---------------------------+
*  28 |         VACVCZCT          |         VACRUNCT          |
*     +---------------------------+---------------------------+
*  30 |         VACWAICT          |         VACMXCPU          |
*     +---------------------------+---------------------------+
*  38 |         VACVCFCT          |         VACRESUM          |
*     +---------------------------+---------------------------+
*  40 |         VACSVGBK          |         VACSKIPS          |
*     +---------------------------+---------------------------+
*  48 |         VACVCFMX          |///////////////////////////|
*     +---------------------------+---------------------------+
*  50 |                       VACORIGF                        |
*     +-------------------------------------------------------+
*  58 |                                                       |
*     =                       VACVCZLK                        =
*     |                                                       |
*     +-------------------------------------------------------+
*  88
*
*** Overlay for VACTKCPE in VACBK

 
Symbol         Dspl Value
-------------- ---- -----
VACABORT       0020 40
VACBSIZE       0058 00000088
VACDONE        0020 20
VACENDTS       0010
VACINPRG       0020 80
VACMXCPU       0034
VACNEXT        0000
VACORIGF       0050
VACPONR        0020 04
VACRESUM       003C
VACRUNCT       002C
VACSIZE        0058 00000011
VACSKIPS       0044
VACSTATU       0020
VACSTRTS       0008
VACSVGBK       0040
VACTASKS       001C
VACTKCPE       0018
VACTOSSC       0004
VACVCFCT       0038
VACVCFMX       0048
VACVCFTH       0020 02
VACVCZCT       0028
VACVCZLK       0058
VACVCZLL       0024
VACWAICT       0030
VACZONFL       0020 01