DIOBK - 64-bit CP - V4R4.0

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

#### DIOBK

Prolog

Control Block Contents
DIOBK DSECT

Storage Layout

Cross Reference (Contains links to field and bit definitions)

#### DIOBK Prolog

     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.

#### DIOBK Control Block Content

#### DIOBK DSECT

    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' Redrive current CRW task.
              .1.. ....      DIOAUTO        X'40' Current task is
                                            IPI-Subchannel Delete CRW task.
              ..1. ....      DIODISC        X'20' Disconnecting a user
              ...1 ....      DIOTTY         X'10' Disconnecting from TTY
    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).
              00000002       DIOBKSIZ       ((*-DIOBK)+7)/8 DIOBK size in
                                            double words.

#### DIOBK Storage Layout

    *** DIOBK - Dynamic I/O control block.
    *
    *     +---------------------------+------+--------------------+
    *   0 |         DIOQUEUE          |:FLAGS|////////////////////|
    *     +---------------------------+------+--------------------+
    *   8 |         DIOCOUNT          | C
    *     +---------------------------+
    *
    *** DIOBK - Dynamic I/O control block.

#### DIOBK Cross Reference

    Symbol         Dspl Value
    -------------- ---- -----
    DIOAUTO        0004 40
    DIOBKSIZ       0008 00000002
    DIOCOUNT       0008
    DIODISC        0004 20
    DIOFLAGS       0004
    DIOQUEUE       0000
    DIOREDRV       0004 80
    DIOTTY         0004 10

This information is based on z/VM V4R4.0. Last updated on 30 Jul 2003 at 12:40:48 EDT.
Copyright IBM Corporation, 1990, 2003