Guardian Procedure Calls Reference Manual

Performance is increased by using KMSF. However, if you want to save the data in the
segment after the process terminates, specify a permanent swap file name. KMSF swap
files have the clear-on-purge attribute, which provides a level of security for swapped data.
For more information on KMSF, see the Kernel-Managed Swap Facility (KMSF) Manual.
• Temporary swap file
If you specify filename, and if filename is a volume name without a subvolume or
file identifier, SEGMENT_ALLOCATE[64]_ creates a temporary swap file on the indicated
volume. You can convert a temporary file to a permanent file by renaming it with the
FILE_RENAME_ procedure.
If you do not specify filename and the alloc-options parameter precludes using
KMSF, SEGMENT_ALLOCATE[64]_ creates a temporary swap file on a volume that it
chooses.
• Existing permanent swap file
If you specify filename and the designated file exists, filename specifies the name of
the swap file to be associated with the segment. All data in the file is used as initial data
for the segment. Remote file names, structured files, audited files, and files with the refresh
attribute are not accepted.
There are two advantages of using an existing swap file. First, if the file is the required
size, segment allocation cannot fail due to lack of disk space. Second, the segment becomes
a permanent repository of data.
If the process terminates without deallocating the segment, any data still in memory is
written back out to the file. Unless the segment is extensible, SEGMENT_ALLOCATE[64]_
must be able to allocate a sufficient number of file extents to contain all memory in the
segment.
• New permanent swap file
If you specify filename, and the designated file does not exist, filename specifies the
name of a swap file to be created. The advantage of using a permanent swap file is that
the segment becomes a permanent repository of data.
If the process terminates without deallocating the segment, any data still in memory is
written back out to the file. Unless the segment is extensible, SEGMENT_ALLOCATE_ must
be able to allocate a sufficient number of file extents to contain all memory in the segment.
• Segment sharing by the file name method
By specifying filename, you can share the segment associated with this swap file with
another process using the same swap file (provided that both processes have appropriate
permission to the file). This is referred to as segment sharing by the file-name method. Two
processes sharing a segment by the file-name method must be in the same processor,
unless the segment is a read-only segment. (See Considerations (page 1268).)
error-detail
output
(for SEGMENT_ALLOCATE_)INT .EXT:ref:1
(for SEGMENT_ALLOCATE64_)INT .EXT64:ref:1
for some returned errors, contains additional information. See Returned Value (page 1267).
SEGMENT_ALLOCATE[64]_ Procedures 1263