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

 
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