DIOBK | Back to Index page

| Prolog Control Block Contents DIOBK 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.

DIOBK Prolog | Top of page

     NAME       : HCPDIOBK
     DESCRIPTION: Dynamic I/O control block.
     DSECT      : DIOBK
     FUNCTION   : 1) Anchor the queue of pending CRW tasks for the
                  corresponding RDEV. A CRW task, or queue element,
                  can be one of the following: IPI - Subchannel Add
                  CRW task, IPI - Subchannel Delete CRW task or IPM
                  CRW task.
                  2) Maintain the count of currently executing CRW
                  AND CRW - related tasks for the corresponding RDEV.
                  CRW - related tasks are invoked by the CRW tasks
                  (IPI - Subchannel Add/Delete CRW task, IPM CRW task).
                  3) Contains a flag field.
     LOCATED BY : RDEVDIO of the corresponding RDEV.
     CREATED BY : HCPRFCDC
     DELETED BY : HCPRFCET
     SERIALIZED : Access to the DIOBK is serialized with the RDEV
                  lock of the corresponding RDEV.
     RELOCATION CONSIDERATIONS : None

DIOBK Control Block Content | Top of page

     DIOBK DSECT
    Top of page

    Hex   Dec Type/Val   Lng Label (dup)    Comments
    ---- ---- --------- ---- -------------- --------
    0000    0 Structure      DIOBK          Dynamic I/O control block.
    0000    0 Address      4 DIOQUEUE       Anchors the queue of pending CRW
                                            tasks for the corresponding RDEV.
                                            (See prolog).
    0004    4 Bitstring    1 DIOFLAGS       Flag field.
              1... ....      DIOREDRV       X'80' DIOREDRV Redrive current
                                            CRW task.
              .1.. ....      DIOAUTO        X'40' DIOAUTO Current task is
                                            IPI-Subchannel Delete CRW task.
              ..1. ....      DIODISC        X'20' DIODISC Disconnecting a
                                            user
              ...1 ....      DIOTTY         X'10' DIOTTY Disconnecting from
                                            TTY
              .... 1...      DIOSTCHG       X'08' DIOSTCHG State Change DIOBK
              .... .1..      DIORFCGD       X'04' DIORFCGD RFC's GETDIOBK
                                            routine was called to build or
                                            use this DIOBK
    0005    5 Bitstring    1 * (3)          (reserved)
    0008    8 Signed       4 DIOCOUNT       The count of currently executing
                                            CRW AND CRW - related tasks for
                                            the corresponding RDEV. (See
                                            prolog).
    000C   12 Signed       4 *              (reserved)
    0010   16 Dbl-Word     8 DIOLOCK (3)    Lockword
              00000005       DIOBKSIZ       ((*-DIOBK)+7)/8 DIOBK size in
                                            double words.

DIOBK Storage Layout | Top of page

    *** DIOBK - Dynamic I/O control block.
    *
    *     +---------------------------+------+--------------------+
    *   0 |         DIOQUEUE          |:FLAGS|////////////////////|
    *     +---------------------------+------+--------------------+
    *   8 |         DIOCOUNT          |///////////////////////////|
    *     +---------------------------+---------------------------+
    *  10 |                                                       |
    *     =                       DIOLOCK                         =
    *     |                                                       |
    *     +-------------------------------------------------------+
    *  28
    *
    *** DIOBK - Dynamic I/O control block.

DIOBK Cross Reference | Top of page

    Symbol         Dspl Value
    -------------- ---- -----
    DIOAUTO        0004 40
    DIOBKSIZ       0010 00000005
    DIOCOUNT       0008
    DIODISC        0004 20
    DIOFLAGS       0004
    DIOLOCK        0010
    DIOQUEUE       0000
    DIOREDRV       0004 80
    DIORFCGD       0004 04
    DIOSTCHG       0004 08
    DIOTTY         0004 10

This information is based on z/VM 7.2.0 Last updated on 24 Jun 2020 at 09:27:46 EDT.
Copyright IBM Corporation, 1990, 2020