DSCBK Back to Index page
 
Prolog 
Control Block Contents 
   DSCBK 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.


  DSCBK Prolog Top of page
  
 NAME       : HCPDSCBK
 DESCRIPTION: Demand Scan Control Block
 DSECT      : DSCBK
 FUNCTION   :
              The Demand Scan Control Block (DSCBK) contains
              information about the Available List Demand Scan
              operation.  The DSCBK is persistent and some
              information is saved between Demand Scans.
 CREATED BY : Assembly at Entry Point HCPRSMSC.
 DELETED BY : none
 RELOCATION CONSIDERATIONS : None
 
 
  DSCBK Control Block Content Top of page
  




 DSCBK DSECT
Top of page


Hex   Dec Type/Val   Lng Label (dup)    Comments
---- ---- --------- ---- -------------- --------
0000    0 Structure      DSCBK          Demand Scan Control Block
0000    0 Signed       4 *              Reserved for IBM use
0004    4 Signed       4 DSCINPUT (0)   Demand Scan Input Word DSCINPUT
                                        is a word of "input status" hints
                                        for other parts of the system to
                                        communicate information "hints"
                                        to demand scan. NOTES : DSCINPUT
                                        fields are NOT serialized, by the
                                        demand scan lock or anything
                                        else.
0004    4 Bitstring    1 *              Reserved
      The following bytes are used to make sure that only
      one CPEBK is stacked for a deferred call to various places.
0005    5 Bitstring    1 *              Reserved
0006    6 Bitstring    1 DSCFMVLK       Indicate that the deferred call
                                        to HCPFMVDS has been stacked
0007    7 Bitstring    1 *              Reserved
0008    8 Bitstring    1 *              reserved
0009    9 Bitstring    1 DSCALRDS       A deferred call to HCPALRDS is
                                        either stacked or running
000A   10 Bitstring    1 * (6)          reserved
0010   16 Signed       4 DSCCYCL        Count the number of scan cycles
0014   20 Signed       4 *              Reserved
      These fields apply to the current Demand Scan.
0018   24 Signed       4 * (2)          Reserved Output from subroutine
                                        CALCMORE in HCPALU. Updated by
                                        CALCMORE. Not changed until the
                                        next call to CALCMORE. These are
                                        "type-any" needs and represent a
                                        current need. (I.E. Deficit
                                        numbers are not factored in.)
0020   32 Dbl-Word     8 DSCREQSingles  Singles Frames needed.
0028   40 Dbl-Word     8 DSCREQContigs  Contigs Frames needed.
0030   48 Dbl-Word     8 DSCSTLW (0)    Steal Write counters (Low/High)
0030   48 Signed       4 DSCSTLW0       Steal Write frames BELOW 2Gb
0034   52 Signed       4 DSCSTLWG       Steal Write frames 2Gb and ABOVE
0038   56 Signed       4 DSCSTLP0       Steal Write PGMBKs BELOW 2Gb
003C   60 Signed       4 DSCSTLPG       Steal Write PGMBKs 2Gb and ABOVE
          00000010       DSCSTLWL       *-DSCSTLW Length of all STL
                                        fields
0040   64 Signed       8 * (6)          Reserved for IBM use
0070  112 Signed       4 *              Reserved for IBM use
      These fields are primarily for diagnostic purposes.
      They should not affect the operation of Demand Scan.
0074  116 Bitstring    1 DSCDEBUG       Debug Flags
          1... ....      DSCACTIV       X'80' DSCACTIV Demand Scan is
                                        ACTIVE
0075  117 Bitstring    3 *              reserved
0078  120 Signed       4 DSCCOUNT       Count the number of times we
                                        entered Demand Scan (HCPALDSC)
007C  124 Signed       4 *              Reserved
0080  128 Signed       4 *              Reserved
0084  132 Address      4 DSCWHOEX       Previous HCPCALL before CALCMORE
0088  136 Signed       4 *              Reserved
008C  140 Signed       4 *              Reserved
0090  144 Signed       8 * (4)          Reserved for IBM use
00B0  176 Signed       4 *              Reserved for IBM use
00B4  180 Signed       4 DSCALSKF       Times an Aging List page was not
                                        taken (i.e. was skipped) because
                                        we couldn't get frame ser.
00B8  184 Signed       4 DSCALSKP       Times an Aging List page was not
                                        taken (i.e. was skipped) because
                                        we couldn't get PTE serializ.
00BC  188 Signed       4 *              Reserved
00C0  192 Signed       4 *              Reserved
00C4  196 Signed       4 *              Reserved
      Communication from the frame manager to subroutine CALCMORE.
00C8  200 Dbl-Word     8 DSCRSingles    (Rate) Need for type any singles.
00D0  208 Dbl-Word     8 DSCRContigs    (Rate) Need for type any contigs.
      CALCMORE data area.
      These values represent harvested rate based information.
      Not technically output, but only used for Demand scan calls.
00D8  216 Dbl-Word     8 DSCHSingles    (Rate) Harvested need for
                                        singles.
00E0  224 Dbl-Word     8 DSCHContigs    (Rate) Harvested need for
                                        contigs.
      These values are the rate based need to use for the current
      call to CALCMORE.  (Either DSCHSingles at the beginning of
      a new Demand scan.   Or a Delta at the end of a Demand scan.)
      Not technically output, but only used for Demand scan calls.
00E8  232 Dbl-Word     8 DSCNSingles    Rate based need for singles.
00F0  240 Dbl-Word     8 DSCNContigs    Rate based need for contigs.
      "Who invoked demand scan" data:
00F8  248 Signed       4 DSCwhoFg (0)
00F8  248 Bitstring    1 DSCwhoRq       Who invoked demand scan (debug
                                        only build) - all requestors
00F9  249 Bitstring    1 DSCwhoFl       Who invoked demand scan (debug
                                        only build) - who actually
                                        flagpoled
      Equates for DSCwhoRq and DSCwhoFl
          1... ....      DSCwhoDSEW     X'80' 1 ALG DSEarlyWrite
          .1.. ....      DSCwhoDSRS     X'40' 2 ALDSC DSRestart
          ..1. ....      DSCwhoTHRS     X'20' 3 ALUDS Threshold
          ...1 ....      DSCwhoAGRV     X'10' 4 PFR AgingRevals
          .... 1...      DSCwhoFRDF     X'08' 5 PTF FrameReqDefer
          .... .1..      DSCwhoLGR      X'04' 6 RLT LGR EQU X'02' 7
                                        Unused.
          .... ...1      DSCwhoAgIn     X'01' 8 ALUDS AgeSizeInc
00FA  250 Bitstring    1 * (2)          Reserved for DSCwhoFg expansion,
                                        must remain 0s
      Array of counts of times each task attempted to flag Demand
      scan to start:
00FC  252 Signed       4 DSCwhoCtArray (8)
                                        (debug only build)
00FC  252 Signed       4 DSCwhoCtDSEW   1 ALG DSEarlyWrite
0100  256 Signed       4 DSCwhoCtDSRS   2 ALDSC DSRestart
0104  260 Signed       4 DSCwhoCtTHRS   3 ALUDS DSThreshold
0108  264 Signed       4 DSCwhoCtAGRV   4 PFR AgingRevals
010C  268 Signed       4 DSCwhoCtFRDF   5 PTF FrameReqDefer
0110  272 Signed       4 DSCwhoCtLGR    6 RLT LGR
0114  276 Signed       4 *              7 Unused.
0118  280 Signed       4 DSCwhoCTAgIn   8 ALUDS AgeSizeInc
011C  284 Bitstring    1 DSC$END (0)    End of DSCBK
          0000011C       DSCBKLN        *-DSCBK DSCBK length (in bytes)
          00000024       DSCBKSZ        (*-DSCBK+7)/8 DSCBK size (in
                                        doublewords)
 
 
  DSCBK Storage Layout Top of page
  
          
*** DSCBK - Demand Scan Control Block
*
*     +---------------------------+------+------+------+------+
*   0 |///////////////////////////|//////|//////|:FMVLK|//////|
*     +------+------+-------------+------+------+------+------+
*   8 |//////|:ALRDS|/////////////////////////////////////////|
*     +------+------+-------------+---------------------------+
*  10 |         DSCCYCL           |///////////////////////////|
*     +---------------------------+---------------------------+
*  18 |///////////////////////////////////////////////////////|
*     +-------------------------------------------------------+
*  20 |                    DSCREQSINGLES                      |
*     +-------------------------------------------------------+
*  28 |                    DSCREQCONTIGS                      |
*     +---------------------------+---------------------------+
*  30 |         DSCSTLW0          |         DSCSTLWG          |
*     +---------------------------+---------------------------+
*  38 |         DSCSTLP0          |         DSCSTLPG          |
*     +---------------------------+---------------------------+
*  40 |///////////////////////////////////////////////////////|
*     =///////////////////////////////////////////////////////=
*     |///////////////////////////////////////////////////////|
*     +---------------------------+------+--------------------+
*  70 |///////////////////////////|:DEBUG|////////////////////|
*     +---------------------------+------+--------------------+
*  78 |         DSCCOUNT          |///////////////////////////|
*     +---------------------------+---------------------------+
*  80 |///////////////////////////|         DSCWHOEX          |
*     +---------------------------+---------------------------+
*  88 |///////////////////////////|///////////////////////////|
*     +---------------------------+---------------------------+
*  90 |///////////////////////////////////////////////////////|
*     =///////////////////////////////////////////////////////=
*     |///////////////////////////////////////////////////////|
*     +---------------------------+---------------------------+
*  B0 |///////////////////////////|         DSCALSKF          |
*     +---------------------------+---------------------------+
*  B8 |         DSCALSKP          |///////////////////////////|
*     +---------------------------+---------------------------+
*  C0 |///////////////////////////|///////////////////////////|
*     +---------------------------+---------------------------+
*  C8 |                     DSCRSINGLES                       |
*     +-------------------------------------------------------+
*  D0 |                     DSCRCONTIGS                       |
*     +-------------------------------------------------------+
*  D8 |                     DSCHSINGLES                       |
*     +-------------------------------------------------------+
*  E0 |                     DSCHCONTIGS                       |
*     +-------------------------------------------------------+
*  E8 |                     DSCNSINGLES                       |
*     +-------------------------------------------------------+
*  F0 |                     DSCNCONTIGS                       |
*     +------+------+-------------+---------------------------+
*  F8 |:WHORQ|:WHOFL|/////////////|                           |
*     +------+------+-------------+                           |
* 100 |                                                       |
*     =                    DSCWHOCTARRAY                      =
*     |                           +---------------------------+
*     |                           | 11C
*     +---------------------------+
*
*** DSCBK - Demand Scan Control Block
          
*** Overlay for DSCwhoCtArray in DSCBK
*
*                                 +---------------------------+
*  F8 ...                      FC |       DSCWHOCTDSEW        |
*     +---------------------------+---------------------------+
* 100 |       DSCWHOCTDSRS        |       DSCWHOCTTHRS        |
*     +---------------------------+---------------------------+
* 108 |       DSCWHOCTAGRV        |       DSCWHOCTFRDF        |
*     +---------------------------+---------------------------+
* 110 |       DSCWHOCTLGR         |///////////////////////////|
*     +---------------------------+---------------------------+
* 118 |       DSCWHOCTAGIN        |
*     +---------------------------+
*
*** Overlay for DSCwhoCtArray in DSCBK
 
 
  DSCBK Cross Reference Top of page
  
 
Symbol         Dspl Value
-------------- ---- -----
DSC$END        011C
DSCwhoAgIn     00F9 01
DSCwhoAGRV     00F9 10
DSCwhoCtArray  00FC
DSCwhoCtAGRV   0108
DSCwhoCtDSEW   00FC
DSCwhoCtDSRS   0100
DSCwhoCtFRDF   010C
DSCwhoCtLGR    0110
DSCwhoCtTHRS   0104
DSCwhoCTAgIn   0118
DSCwhoDSEW     00F9 80
DSCwhoDSRS     00F9 40
DSCwhoFg       00F8
DSCwhoFl       00F9
DSCwhoFRDF     00F9 08
DSCwhoLGR      00F9 04
DSCwhoRq       00F8
DSCwhoTHRS     00F9 20
DSCACTIV       0074 80
DSCALRDS       0009
DSCALSKF       00B4
DSCALSKP       00B8
DSCBKLN        011C 0000011C
DSCBKSZ        011C 00000024
DSCCOUNT       0078
DSCCYCL        0010
DSCDEBUG       0074
DSCFMVLK       0006
DSCHContigs    00E0
DSCHSingles    00D8
DSCINPUT       0004
DSCNContigs    00F0
DSCNSingles    00E8
DSCRContigs    00D0
DSCREQContigs  0028
DSCREQSingles  0020
DSCRSingles    00C8
DSCSTLPG       003C
DSCSTLP0       0038
DSCSTLW        0030
DSCSTLWG       0034
DSCSTLWL       003C 00000010
DSCSTLW0       0030
DSCWHOEX       0084
 
This information is based on z/VM 7.1.0 Last updated on 22 Jun 2018 at 11:49:11 EDT.
Copyright IBM Corporation, 1990, 2018