System Control Blocks

Offset
-16 (-10) 1
-15 (-F) • 7
-8 (-8) 4
-4 (-4) 1
-3 (-3) • 3
0 (0) 1
1 (1) • 3
4 (4) 1
5 (5) • 3
8 (8) 9
17 (11) • 3
20 (14) 1
21 (15) • 3
24 (18) 1
25 (19) • 3
28 (lC) 1
29 (10) • 3
32 (20) 4
36 (24) 1
37 (25) • 3
40 (28) 5
45 (20) • 3
Bytes and
Alignment
PREFIX
DATA EXTENT BLOCK -- QTAM
Field Description, Contents, Meaning
MESSAGE PROCESS QUEUE
Work area used by I/O support routines.
Direct access device address used by I/O support routines. Format
(BBCCHHR)
DCB modification mask used by I/O support routines.
Length of this DEB.
Reserved.
BASIC SECTION
Reserved.
Address of the TCB.
Reserved.
DEB PROPER
Address of the next DEB in the same task.
Reserved.
Address of the next available record of the process queue on the
direct access device.
Reserved.
Address of the next DEB on the chain of the process program's DEBs.
X'OF'; identifies this block as a DEB.
Address of the DCB.
Reserved.
Address of the beginning of the tuffer request block (BRB) portion
of this DEB.
Address of a dummy LeB.
QUEUE CONTROL BLOCK
Reserved.
Address of dummy last entry in queue.
Reserved.
Address of QPRIRITY subtask.
130 OS System Control Blocks (Release 21.7)