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• Release of data extent block (DEB).
• Removal of information transferred to data control block fields when
OPEN was executed.
• Verification or creation of standard labels.
• Release of programmer-written appendage routines.
The only parameter of the CLOSE macro-instruction is the
address
of
the
data
control
block
to
be restored.
(More than one data control
block may be specified.)
THE XDAP CONTROL BLOCK
The three portions of the control block generated during execution of
the XDAP macro-instruction are described here.
Event Control Block (ECB)
The event control block begins on a full word boundary
and
occupies
the
first
4
bytes
of
the XDAP control block.
Each time the direct-
access channel program terminates, the input/output supervisor places
a
completion
code
containing
status
inforrr.ation into the event control
block (Figure 12).
Before examining this information, you must test for
the setting of the "Complete Bit" by issuing
a
WAIT
macro-instruction
specifying the event control block.
r--------------T------------------T------------------------------------,
I
WAIT Bit=O
I
Complete Bit=l
I
Remainder of Completion Code
I
L ______________
~
__________________
~
____________________________________ J
o
1
2
31
Figure 12.
Event Control Block After Posting of Completion Code
WAIT Bit
A
one
bit
in
this
position
instruction has been issued, but
program has not been completed.
indicates
that
the
WAIT
that
the
direct-access
macro-
channel
Corrplete Bit
A
one
bit in this position indicates that the channel program has
been completed; if it has not been completed, a zero bit is in this
position.
Completion Code
102
This code, which includes the WAIT and Complete bits, may be one of
the following 4-byte hexadecimal expressions:
7FOOOOOO
41000000
42000000
44000000
Interpretation
Direct-access program
has
terminated
without
error.
Direct-access
program
has
permanent error.
terminated
with
Direct-access
program has terminated because a
direct-access extent address has been violated.
Channel program has been intercepted because of
perrranent errcr associated with device end
for
previous
request.
You may reissue the inter-
certed request.
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