DIOBK

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