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Prolog 
Control Block Contents 
   FSCBK 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.


  FSCBK Prolog Top of page
 
 NAME       : HCPFSCBK
 DESCRIPTION: Free Storage Counter Block
 DSECT      : FSCBK
 FUNCTION   : Storage accounting for control blocks used in
              the free storage limit detection function.
 LOCATED BY : VMDFSCBK field of HCPVMDBK
 CREATED BY : HCPBVM for an origin VMDBK. Non-origin VMDBKs
              are assigned the address of the origin FSCBK.
 DELETED BY : HCPUSP deletes the FSCBK when the origin VMDBK
              logs off if FSCCOUNT is zero, Otherwise it will
              be released when HCPFRGDC decrements FSCCOUNT
              to zero.
 SERIALIZED : Informal spin lock FSCLOCK will be used to
              serialize the FSCCOUNT, FSCGRACE and FSCFLAG
              fields.
 
 
  FSCBK Control Block Content Top of page
 

 FSCBK DSECT Top of page
Hex Dec Type/Val Lng Label (dup) Comments ---- ---- --------- ---- -------------- -------- 0000 0 Structure FSCBK Free Storage Counter Block 0000 0 Dbl-Word 8 FSCUSER (0) Userid if user has logged off. 0000 0 Signed 4 FSCVMDBK Origin VMDBK address if user is logged on. 0004 4 Signed 4 * Reserved for IBM use. 0008 8 Dbl-Word 8 FSCGRACE Timestamp for grace period. FSCLOCK must be held to update this field. 0010 16 Signed 4 FSCCOUNT Number of doublewords of free storage currently held by user for monitored control blocks. FSCLOCK must be held to update this field. 0014 20 Signed 4 FSCSTATS (0) Limit detection status 0014 20 Bitstring 1 * (3) Reserved for IBM use. 0017 23 Bitstring 1 FSCFLAG Flags. Serialized with FSCLOCK. .1.. .... FSCWRNG X'40' FSCWRNG Warning message was issued. ..1. .... FSCSTOP X'20' FSCSTOP Virtual machine is placed in a stopped sta 2nd message was issued. ...1 .... FSCFORCE X'10' FSCFORCE Logoff message was issued. .... 1... FSCEXMPT X'08' FSCEXMPT User is exempt from the stop and force ac of the free storage limit detection function. .... .1.. FSCGRCON X'04' FSCGRCON A 1 minute grace period is allowed 0018 24 Signed 4 FSCLOCK This is an informal spin lock. The lock must be held to update COUNT, GRACE and FLAGS. Use test and set to update. 00000004 FSCSIZE ((*-FSCBK)+7)/8 FSCBK size in double-words
 
 
  FSCBK Storage Layout Top of page
 
          
*** FSCBK - Free Storage Counter Block
*
*     +---------------------------+---------------------------+
*   0 |         FSCVMDBK          |///////////////////////////|
*     +---------------------------+---------------------------+
*   8 |                       FSCGRACE                        |
*     +---------------------------+--------------------+------+
*  10 |         FSCCOUNT          |////////////////////|:FLAG |
*     +---------------------------+--------------------+------+
*  18 |         FSCLOCK           | 1C
*     +---------------------------+
*
*** FSCBK - Free Storage Counter Block
 
 
  FSCBK Cross Reference Top of page
 
 
Symbol         Dspl Value
-------------- ---- -----
FSCCOUNT       0010
FSCEXMPT       0017 08
FSCFLAG        0017
FSCFORCE       0017 10
FSCGRACE       0008
FSCGRCON       0017 04
FSCLOCK        0018
FSCSIZE        0018 00000004
FSCSTATS       0014
FSCSTOP        0017 20
FSCUSER        0000
FSCVMDBK       0000
FSCWRNG        0017 40
 
This information is based on z/VM 7.3.0 Last updated on 22 Jun 2022 at 15:50:46 EDT.
Copyright IBM Corporation, 1990, 2022