At 09:53 -0500 on 11/06/2010, Scott Barry wrote about Re: IDCAMS
ALTER and GDGs - From A(0) to B(+1) - Relative G:
If a tape dataset name is 17 characters or longer (and the last 17
characters do not change), I believe that it can be renamed, using a DEFINE
NVSAM command (with DEVTYPE, VOLUMES and optionally FSEQN), along with the
requisite DELETE '<dsn>' NOSCRATCH command. At least with CA-1, there are
TMC update utilities TMSUPDTE and TMSUDSNB ("restricted use" though), as
well, to consider using with this activity, where any DSN length is a
candidate for change.
Scott Barry
SBBWorks, Inc.
Interestingly the fact that only the LAST 17 characters of a 18-44
character dataset name are stored in a TAPE HDR1/EOF1/EOV1 label
allows the dataset to be renamed and still be acceptable so long as
the last 17 remain constant and the 1-27 character prefix is changed.
For GDGs, the .GxxxxVyy is stored as the last 9 characters leaving
only 8 characters of the actual name for comparing to the supplied
18-44 character DSN. Since the Gxxx and Vyy are replicated as
separate fields in the labels, IN THEORY, for 18-27 character GDG
names the name could fully be stored in the labels by storing the
1-17 character GDG Base Name in the DSN area and the Gxxxx and Vyy
values in their dedicated fields thus closing this loophole for under
26 character long GDG Dataset Names stored on Tape.
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