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| Prolog Control Block Contents Threshold 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.

THRESHOL Control Block Content | Top of page

     Threshold DSECT
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    Hex   Dec Type/Val   Lng Label (dup)    Comments
    ---- ---- --------- ---- -------------- --------
    0000    0 Structure      Threshold      RSM common area mapping
    0000    0 Signed       4 ThreshPT       Protect threshold.
    0004    4 Signed       4 ThreshHT       High threshold.
    0008    8 Signed       4 ThreshLT       Low threshold.
    000C   12 Signed       4 ThreshISG      Initial value set by ALUSR.
    0010   16 Signed       4 *              Low water mark. Too expensive.
    0014   20 Signed       4 ThreshIncZ     Times incremented, hit zero.
    0018   24 Signed       4 ThreshIncCnt   Times Incremented, too close to
                                            0.
    001C   28 Signed       4 ThreshDecCnt   Times Decremented.
    0020   32 Signed       4 ThreshGood     Times Good. NB: The ThreshCond
                                            field is set with a MVI.
    0024   36 Bitstring    1 *              Current condition of the UGALs
                                            regarding the request type.
                                            Entire field set with MVIy only.
              1... ....      AbovePT        X'80' count > PT
              .1.. ....      AtAboveHT      X'40' count >= HT
              ..1. ....      AtAboveLT      X'20' Count >= LT
              ...1 ....      BelowLT        X'10' Count < LT
    0025   37 Bitstring    1 ThreshTFg      Flag used for adjustment of
                                            thresholds. Serialization note:
                                            There is no serialization for
                                            this byte. OI/NI are used to turn
                                            bits on and off, MVIy is used to
                                            reset the byte. A progressive
                                            system is used such that a missed
                                            update will not matter.
              1... ....      PTTransA       X'80' Set when at/above PT
                                            observed.
              .1.. ....      HTTransA       X'40' Set when at/above HT
                                            observed.
              ..1. ....      LTTransA       X'20' Set when at/above LT
                                            observed.
              ...1 ....      LTTransD       X'10' Set when below LT observed.
              .... 1...      HTSeen         X'08' HCPALU:CheckLT has seen
                                            HTTransA
              .... .1..      DSSeen         X'04' HCPALU:CheckLT has seen DS
                                            run.
              .... ..1.      DSESeen        X'02' HCPALU:CheckLT has seen DS
                                            end.
              .... ...1      JB             X'01' Journey Begins
    0026   38 Bitstring    2 *              Reserved
    0028   40 Signed       8 ThreshDebug
         | Define a local DSECT that maps the first 3 fields of     |
         | the many system execution space queues.

THRESHOL Storage Layout | Top of page

    *** Threshold - RSM common area mapping
    *
    *     +---------------------------+---------------------------+
    *   0 |         THRESHPT          |         THRESHHT          |
    *     +---------------------------+---------------------------+
    *   8 |         THRESHLT          |        THRESHISG          |
    *     +---------------------------+---------------------------+
    *  10 |///////////////////////////|        THRESHINCZ         |
    *     +---------------------------+---------------------------+
    *  18 |       THRESHINCCNT        |       THRESHDECCNT        |
    *     +---------------------------+------+------+-------------+
    *  20 |        THRESHGOOD         |//////|(025) |/////////////|
    *     +---------------------------+------+------+-------------+
    *  28 |                     THRESHDEBUG                       |
    *     +-------------------------------------------------------+
    *  30
    *
    *** Threshold - RSM common area mapping

THRESHOL Cross Reference | Top of page

    Symbol         Dspl Value
    -------------- ---- -----
    AbovePT        0024 80
    AtAboveHT      0024 40
    AtAboveLT      0024 20
    BelowLT        0024 10
    DSESeen        0025 02
    DSSeen         0025 04
    HTSeen         0025 08
    HTTransA       0025 40
    JB             0025 01
    LTTransA       0025 20
    LTTransD       0025 10
    PTTransA       0025 80
    ThreshDebug    0028
    ThreshDecCnt   001C
    ThreshGood     0020
    ThreshHT       0004
    ThreshIncCnt   0018
    ThreshIncZ     0014
    ThreshISG      000C
    ThreshLT       0008
    ThreshPT       0000
    ThreshTFg      0025

This information is based on z/VM 7.2.0 Last updated on 24 Jun 2020 at 09:30:12 EDT.
Copyright IBM Corporation, 1990, 2020