How do you initialize a VSAM file before any operation?

patlolla · New User Joined: 05 Jun 2006 Posts: 10

How do you initialize a VSAM file before any operation? a VSAM with alternate index?

expat · Posted: Wed Oct 21, 2009 2:09 pm

Write a dummy record into the base cluster.
Usually a record with a key value of either low or high values.

Pete Wilson · Posted: Tue Jan 05, 2010 9:24 pm

There's program around called VSAMINIT that can insert and optionally delete a record into VSAM files including AIX's. We use it regularly to prime CICS datasets because CICS fails to open empty newly defined VSAM files.

There's plenty of examples if you google it...e.g. www.system-support.com/vsaminit.asm provides source code and example JCL. We have found some occasions that ESDS's inexplicably won't work with this.

PeterHolland · Posted: Tue Jan 05, 2010 9:33 pm

To use your own program to load a key-sequenced data set, first sort the records (or build them) in key sequence, then store them sequentially. When you are initially loading a data set, direct access is not permitted.

Even IDCAMS REPRO can fill an empty vsam dataset, without any initializing.

PeterHolland · Posted: Tue Jan 05, 2010 9:55 pm

B.t.w i forgot to mention the following :

A data set in VSAM load mode cannot have alternate indexes in the upgrade set. If you want to create and load a data set with alternate indexes, you must use AMS, or some other suitable batch program, to load the data set and invoke BLDINDEX to create the alternate indexes.