Programming Interface Information: This information is NOT intended to be used as Programming Interfaces of z/VM.

#### LATBK

Prolog

Control Block Contents
LATBK DSECT

Storage Layout

Cross Reference (Contains links to field and bit definitions)

#### LATBK Prolog

     Name       : HCPLATBK
     Description: C System Services Latch block
     DSECT      : LATBK
     Function   : C System Services Latch block used to describe the
                  suspend lock used by platform specific C Services
     Located by : Passed as argument on latch, unlatch, testLatch
                  and eventWait services
     Created by : allocateLatch service
     Deleted by : deallocateLatch service
     Serialized : None
     Notes      : This COPY file is modeled after HCPLKWRD so
                  existing CP lock routines could be utilized.

#### LATBK Control Block Content

#### LATBK DSECT

    Hex   Dec Type/Val   Lng Label (dup)    Comments
    ---- ---- --------- ---- -------------- --------
    0000    0 Structure      LATBK          C System Services Latch block
    0000    0 Dbl-Word     8 LATCSWAP (0)   Doubleword updated by Compare and
                                            Swap
    0000    0 Signed       4 LATSTATE       Current lock state.
    0004    4 Address      4 LATQUEUE       Pointer to chain of deferred
                                            CPEBK's
    0008    8 Dbl-Word     8 LATQQTOD       TOD saved at last
                                            enqueue/dequeue. (Only stamped if
                                            there's a queue.)
    0010   16 Bitstring    1 LATFLG1        Miscellaneous lock flags (not
                                            used in C code - for CP
                                            compatibility)
    0011   17 Bitstring    3 LATDQLEN       Current length of defer queue.
    0014   20 Signed       4 LATDYTOD       TOD saved at start of last
                                            "delay"
    0018   24 Dbl-Word     8 LATTHRED       Pointer to thread which holds
                                            latch
              00000020       LATBSIZE       *-LATBK size in bytes
              00000004       LATSIZE        (*-LATBK+7)/8 size in double
                                            words

#### LATBK Storage Layout

    *** LATBK - C System Services Latch block
    *
    *     +---------------------------+---------------------------+
    *   0 |         LATSTATE          |         LATQUEUE          |
    *     +---------------------------+---------------------------+
    *   8 |                       LATQQTOD                        |
    *     +------+--------------------+---------------------------+
    *  10 |:FLG1 |     LATDQLEN       |         LATDYTOD          |
    *     +------+--------------------+---------------------------+
    *  18 |                       LATTHRED                        |
    *     +-------------------------------------------------------+
    *  20
    *
    *** LATBK - C System Services Latch block

#### LATBK Cross Reference

    Symbol         Dspl Value
    -------------- ---- -----
    LATBSIZE       0018 00000020
    LATCSWAP       0000
    LATDQLEN       0011
    LATDYTOD       0014
    LATFLG1        0010
    LATQQTOD       0008
    LATQUEUE       0004
    LATSIZE        0018 00000004
    LATSTATE       0000
    LATTHRED       0018

This information is based on z/VM V5R2.0. Last updated on 12 Apr 2006 at 17:00:33 EDT.
Copyright IBM Corporation, 1990, 2005