SHRBK | Back to Index page

| Prolog Control Block Contents SHRBK 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.

SHRBK Prolog | Top of page

     NAME       : HCPSHRBK
     DESCRIPTION: SHARE BLOCK
     DSECT      : SHRBK
     FUNCTION   : This block is used to keep track of each NSS or DCSS
                  that a user is attached to.
     LOCATED BY : All SHRBKs for the NSS and/or DCSSs that the
                  virtual machine user is accessing are chained
                  together in a list anchored off the VMDBK.
                  VMDSHRPT is the pointer to the first SHRBK
                  for this user.  A zero pointer indicates
                  that the user's chain is empty.
                  SHRFWDPT is the pointer to the next SHRBK
                  in the user's chain. The chain end is
                  indicated when SHRFWDPT is zero.
                  - All SHRBKs for users using a specific SNTBK are
                  chained together in a doubly linked list
                  anchored off the SNTBK.  This list represents
                  all users who have loaded the NSS or DCSS.
                  SNTSHRPT is the pointer to the first SHRBK
                  in the chain for this SNTBK.  A zero pointer
                  indicates that the chain is empty.
                  SHRQUEFW is the pointer to the next SHRBK
                  in the chain for this SNTBK.  The chain end
                  is indicated when SHRQUEFW is zero.
                  SHRQUEBK is the pointer to the previous SHRBK
                  in the chain for this SNTBK.
     CREATED BY : HCPNSL when loading an NSS or DCSS.
     DELETED BY : HCPNSP - when the user purges the DCSS.
                  HCPNSP - when the user IPLs a system, all
                  SHRBKs for that user are purged.
     RELOCATION CONSIDERATIONS : None
     COMMENTS   : None.

SHRBK Control Block Content | Top of page

     SHRBK DSECT
    Top of page

    Hex   Dec Type/Val   Lng Label (dup)    Comments
    ---- ---- --------- ---- -------------- --------
    0000    0 Structure      SHRBK          SHARE BLOCK
    0000    0 Address      4 SHRFWDPT       Forward pointer to this user's
                                            next SHRBK.
    0004    4 Address      4 SHRSNTPT       Pointer to the SNTBK for this NSS
                                            or DCSS.
    0008    8 Character    8 SHRNAME        The name for this NSS or DCSS.
    0010   16 Signed       4 SHRFLAGS (0)   Flags for SHRBK.
    0010   16 Bitstring    1 SHRTYPE        Type information byte.
              .... ...1      SHREXCL        X'01' SHREXCL This bit indicates
                                            that the NSS or DCSS is an
                                            exclusive copy.
    0011   17 Bitstring    1 * (3)          Reserved for IBM use.
    0014   20 Address      4 SHRVMDBK       @ of VMDBK that owns this SHRBK.
    0018   24 Address      4 SHRQUEFW       Next SHRBK on a chain of SHRBKs
                                            associated with a specific SNTBK.
    001C   28 Address      4 SHRQUEBK       Prev.SHRBK on a chain of SHRBKs
                                            associated with a specific SNTBK.
    0020   32 Address      4 SHRLSSA        Address of the SNTBK defining the
                                            segment space through which the
                                            named member segment was loaded.
                                            When this field is equal to
                                            SHRSNTPT, SHRNAME is not a member
                                            segment. It is a named saved
                                            segment or segment space.
    0024   36 Signed       4 *              Reserved for IBM use
              00000005       SHRSIZE        ((*-SHRBK+7)/8) Block in double
                                            words.

SHRBK Storage Layout | Top of page

    *** SHRBK - SHARE BLOCK
    *
    *     +---------------------------+---------------------------+
    *   0 |         SHRFWDPT          |         SHRSNTPT          |
    *     +---------------------------+---------------------------+
    *   8 |                       SHRNAME                         |
    *     +------+--------------------+---------------------------+
    *  10 |:TYPE |////////////////////|         SHRVMDBK          |
    *     +------+--------------------+---------------------------+
    *  18 |         SHRQUEFW          |         SHRQUEBK          |
    *     +---------------------------+---------------------------+
    *  20 |         SHRLSSA           |///////////////////////////|
    *     +---------------------------+---------------------------+
    *  28
    *
    *** SHRBK - SHARE BLOCK

SHRBK Cross Reference | Top of page

    Symbol         Dspl Value
    -------------- ---- -----
    SHREXCL        0010 01
    SHRFLAGS       0010
    SHRFWDPT       0000
    SHRLSSA        0020
    SHRNAME        0008
    SHRQUEBK       001C
    SHRQUEFW       0018
    SHRSIZE        0024 00000005
    SHRSNTPT       0004
    SHRTYPE        0010
    SHRVMDBK       0014

This information is based on z/VM 7.2.0 Last updated on 24 Jun 2020 at 09:30:29 EDT.
Copyright IBM Corporation, 1990, 2020