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Prolog 
Control Block Contents 
   LOCBK 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.


  LOCBK Prolog Top of page
  
 NAME       : HCPLOCBK
 DESCRIPTION: C System Services Lock block
 DSECT      : LOCBK
 FUNCTION   : C System Services Lock block used to describe the
              spin lock used by platform specific C Services
 LOCATED BY : Passed as argument on lock, unlock, testLock
              and eventWait services
 CREATED BY : allocateLock service
 DELETED BY : deallocateLock service
 SERIALIZED : CP lock routines
 RELOCATION CONSIDERATIONS : None
 NOTES      : LOCSLOCK is defined to be the size of a SYNBK so
              that it can be mapped with by the SYNBK. LOCLOCK
              maps the first dword of SYNBK; i.e. SYNLOCKD.
              This control block is allocated from SHORTTERM
              free storage, but of 29 dwords so that when the
              header and trailer are added it is cache aligned
              and uses the entire cache line. This is to avoid
              what appears to be spinlock contention but is
              cache line contention from different locks in the
              same cache line.
 
 
  LOCBK Control Block Content Top of page
  




 LOCBK DSECT
Top of page


Hex   Dec Type/Val   Lng Label (dup)    Comments
---- ---- --------- ---- -------------- --------
0000    0 Structure      LOCBK          C System Services Lock block
0000    0 Signed       8 LOCSLOCK (6)   Spin lock
0030   48 Address      8 LOCTHRED       Pointer to thread which holds
                                        lock
          00000038       LOCUSED        (*-LOCBK) Size of used LOCBK
                                        space.
0038   56 Bitstring    1 * (176)        Reserved for IBM use.
          000000E8       LOCBSIZE       *-LOCBK size in bytes
          0000001D       LOCSIZE        (*-LOCBK+7)/8 size in double
                                        words
0000    0 Signed       8 LOCLOCK        First doubleword of the lock area
 
 
  LOCBK Storage Layout Top of page
  
          
*** LOCBK - C System Services Lock block
*
*     +-------------------------------------------------------+
*   0 |                                                       |
*     =                       LOCSLOCK                        =
*     |                                                       |
*     +-------------------------------------------------------+
*  30 |                       LOCTHRED                        |
*     +-------------------------------------------------------+
*  38 |///////////////////////////////////////////////////////|
*     =///////////////////////////////////////////////////////=
*     |///////////////////////////////////////////////////////|
*     +-------------------------------------------------------+
*  E8
*
*** LOCBK - C System Services Lock block
          
*** Overlay for LOCSLOCK in LOCBK
*
*     +-------------------------------------------------------+
*   0 |                       LOCLOCK                         |
*     +-------------------------------------------------------+
*   8
*
*** Overlay for LOCSLOCK in LOCBK
 
 
  LOCBK Cross Reference Top of page
  
 
Symbol         Dspl Value
-------------- ---- -----
LOCBSIZE       0038 000000E8
LOCLOCK        0000
LOCSIZE        0038 0000001D
LOCSLOCK       0000
LOCTHRED       0030
LOCUSED        0030 00000038
 
This information is based on z/VM 7.2.0 Last updated on 24 Jun 2020 at 09:29:00 EDT.
Copyright IBM Corporation, 1990, 2020