A very long time ago (over 30 years ago) I worked for a service bureau.\
They had specific naming standards for their libraries when products were
installed (ie. SYSx.product.V01R03.LOADLIB).
We couldn't have our customers continually changing JCL unless they wanted a
different version than what was installed so we created a system tool called
"Virtual Dataset Names".
This worked very similar to how ALIAS names works although there was no "must
be in the same catalog" restriction.
When the system was IPL'd (or later via a special operator command) a table was
loaded into CSA that contained the REAL dataset name, the VIRTUAL name and the
various versions that were available. One of the versions was marked as the
default.
We used the IGG026DU catalog front-end exit (which I believe is now used by
DFSMSHSM) to intercept catalog lookups and replace the REAL name that is being
located with the VIRTUAL name. It would scan SWA and check if an ACCT= was
specified on the EXEC statement. If so, the 1st operand was used to overriding
VERION for all datasets within that step.
Example:
//step50 exec pgm=iefbr15,ACCT=V5R3
//DD1 dd dsn=sys1.sortlib,disp=shr
If SYS1.SORTLIB is in the table and it's virtual name is PROD.?.SORTLIB and it
had a list of versions, V1R0 being the alias, DD1 would be translated to
PROD.V5R3.SORTLIB as ACCT=V5R3 was specified. If it wasn't DD1 would be
PROD.V1R0.SORTLIB.
Our customers loved this as they could test NEW versions of products before
they became the default.
If someone has the time, maybe they could take on this project and re-write
this cool tool ;-)
Dan
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