CA Dynam for VSE User Guide

Processing Unchained Multifile Tapes
The first DSN in the unchained multifile set dictates all volume criteria,
density, tape length, and so on, for that tape and subsequent files, regardless
of what is specified on the TLBL or the Catalog.
All output $TEST multifile data sets (unchained or predefined) are created as
single file data sets with a file sequence of one on separate volumes.
Unchained multifile versions are scratched when they become eligible
regardless of the location of the file on the tape. After a volume contains no
active files (all unchained files are in scratch status), the volume is returned to
scratch status.
File sequence numbers for unchained multifile versions are relative to the start
of the volume on which the file exists. File sequence numbers for predefined
multifiles are relative to the volume that starts the whole multifile set. In
effect, the file sequence for unchained versions start over with each new tape
volume, where predefined versions continue incrementing from the first file on
the first volume of the set.
The following illustrates this point:
DSN VOLSER FILESEQ FILESEQ
PREDEFINED UNCHAINED
dsn1 tape01 1 1
dsn2 tape01 2 2
tape02 2 1
dsn3 tape02 3 2
dsn4 tape02 4 3
tape03 4 1
The following JCL examples show how to create multifile data sets using the
STACK= option.
Examples:
Adding a file to an active tape
Note: REF must be used as the DTFNAME and filea must be the last active file
on that VOLSER.
// TLBL REF,'filea',STACK=A
// TLBL NEWFILE,'fileb',STACK=A
// EXEC pgm
Create a new multifile set on a scratch volume:
// TLBL OUT1,'filea',STACK=B
// TLBL OUT2,'fileb',STACK=B
// TLBL OUT3,'filec',STACK=B
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