Control Data Corporation 3300 Reference Manual page 102

4-22
Single or multi -reel files are rewound; the file is positioned at its beginning
on the last (or only) used reel. The previous reels are not affected.
If a mass storage file is described with a FILE LIMITS clause, the input-
output control system automatically releases the unused portion of the area
allocated to the file when the file is closed. For a mass storage file CLOSE
UNIT has the same effect as CLOSE FILE.
CLOSE WITH LOCK applies only to tape files.
It
performs the standard close
operations for single-reel and multi-reel files, rewinds the file, and unloads
it. The file is no longer available for processing.
CLOSE WITH NO REWIND applies only to tape files. The file is closed with
the standard close procedures but the current reel remains in its current
position.
When multi-reel files are closed, previous reels are not affected unless
controlled by a prior CLOSE REEL.
If
the current reel is not the last in an
input file, succeeding reels are not processed in any way. CLOSE REEL
applies only to multi-reel tape files. The following operations are performed
in a standard close reel:
Input files:
Reel swap and standard beginning reel label and user's be-
ginning reel label procedures (if specified by USE). Order of
execution is specified in USE statement.
Makes available the next data record on the new reel.
Output files: Standard ending reel label and user's ending reel procedure
(if specified by USE). Order of execution is specified in
USE statement.
Reel swap and standard beginning reel label procedure and
user's beginning reel label procedure if specified by USE.
The file is rewound, positioned at its beginning on the last used reel.
CLOSE REEL WITH LOCK causes the standard close reel operations to be
performed on the current reel of a multi-reel tape file. In addition, the
reel is rewound and unloaded. The reel cannot be processed again as a
part of the file.
CLOSE REEL WITH NO REWIND causes the standard close reel operations
to be performed on the current reel of a multi-reel tape file but the reel is
left in its current position.
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