CA Dynam for VSE User Guide

Using CA Dynam/T
Using the Early Drive Release
When necessary, the Automatic Volume Recognition facility automatically
positions multifile data sets. In conjunction with AVR, the Early Drive Release
facility releases a tape unit assignment as soon as the accessed file is closed
by the problem program. Together, these facilities maximize the efficiency of
tape units in a multiprogramming environment, as follows:
• A tape unit is assigned only while in actual use between OPEN and CLOSE
of the accessed file, instead of remaining assigned for the duration of an
entire job.
• For multivolume files, the volume switch can take place as soon as EOV
occurs. Alternate assignments requiring that two tape units be assigned
while only one is in use are not necessary.
You can override the AVR facility at any time through JCL assignments. It can
also be limited to selected drives through the DTPOOL option record.
Dynamic LUB Allocation
Dynamic LUB allocation is performed automatically, unless specifically
prohibited on the TLBL or with the DTLUBEX option record. The order in which
CA Dynam/T allocates LUB for a tape DTF is as follows:
1. Logical unit as specified with the S:nnn option of the TLBL statement (LUB
override).
2. Logical unit as found in the user DTF.
3. Logical unit as defined for the partition in the COMLUB option record.
4. Highest logical unit in the partition assigned UA.
To exclude a particular file from dynamic LUB allocation, code the P (to
prohibit) or H option (to hold) on the TLBL statement. The DTLUBEX option
record can be used to exclude a group of DTF names or phase names from
dynamic LUB allocation.
Note: To prohibit dynamic LUB allocation entirely, specify either DTFNAME=*
or PHASNAME=* in the DTLUBEX option record.
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