System Control Blocks

Offset
41 (29) • 3
44 (2C) 4
45 (2D) • 3
Bytes and Field
Alignment Name
32 (20) n times
1
• 3
+0 1
+1 • 3
1
• 3
32 (20) 1
33 (21) • 3
36 (24) 1
37 (25) • 3
40 (28) 1
41 (29) • 3
44 (2C) 4
1
+0 1
• 3
+1 .. 3
DEBPDCBA
DEBWDCB
DEBWOCBA
DEBUCBAD
DEBUCBAD 1
DEBUCBADn
DEBNIEE
DEBFIEAD
DEBNPEE
DEBFPEAD
DEBNOEE
DEBFOEAD
DEB EX PI'
DEBRPSID
1 •••
• 1 ••
•• 1.
••• 1
xxxx
DEBEXPTA
DEBDVMOD
DEBUCBAD
DATA EXTENT BLOCK -- ORDINARY
Field Description, Contents, Meaning
IBM 3525 CARD PUNCH (Continued)
The address of the DCB for the PUNCH associated data
set.
The address of the DCB for the PRINT associated data
set.
TELECOMMUNICATIONS DEVICES
List of addresses (n) of UCBs for lines (n).
Reserved.
Address of the UCB for the line.
GRAPHIC DEVICES
Reserved.
122 OS System Control Blocks (Release 21.7)
Pointer to first UCB.
Reserved.
Pointer to last UCB.
ISAM-DEPENDENT DEVICE SECTION
Present only if ISAM is used. Follows the basic
section. Precedes the direct access storage device
section. Counted as one extent in DEBNMEXT.
Number of extents of independent index area.
Address of first index extent.
Number of extents of prime data area.
Address of the first prime data extent.
Number of extents of independent overflow area.
Address of the first overflow extent.
Rotational position senSing (RPS) device indicators.
DEBRPSP-Prime data area is on RPS device.
DEBRPSI-Independent index area is on RPS device •
DEBRPSO-Independent overflow area is on RPS device •
DEBRPSAP-RPS SIO appendage has been loaded •
(Reserved bits).
Address of ISAM access method dependent section.
DIRECT-ACCESS STORAGE DEVICES
EXTENT DESCRIPTION SEGMENTS:
For each extent there is a 16-byte segment as
follows.
Device modifier: file mask.
Address of UCB associated with this data extent.