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Dynamic Space Reclaim for VSAM Data Sets

IP.com Disclosure Number: IPCOM000226355D
Publication Date: 2013-Mar-30
Document File: 2 page(s) / 62K

Publishing Venue

The IP.com Prior Art Database

Abstract

Disclosed is a new method to reclaim the existing empty Control Areas (CAs) of the Virtual Storage Access Method (VSAM) Key-Sequenced Data Sets (KSDS) without requiring that the data set be taken off-line or closing the data set. This is accomplished by taking advantage of the function of CA Reclaim.

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Dynamic Space Reclaim for VSAM Data Sets

With a 64-bit operating system for mainframe computers, customers have the ability to specify Control Area (CA) Reclaim for their Virtual Storage Access Method (VSAM) Key-Sequenced Data Sets (KSDS). CA Reclaim will reclaim a CA once the last record from that CA has been erased. If a data set was processed prior to CA Reclaim being enabled, there could be empty CAs in the data set from before, and there is still no way to delete these CAs. If these ranges of keys are not accessed again, these CAs remain empty and unused, so even CA Reclaim will not help in this situation. These empty CAs obviously take up space on the Direct Access Storage Device (DASD) and degrade record access performance when there are a large number of them.

Currently, the common way to remove them and reclaim that space is to reorganize the dataset with a known utility. However, this means closing the data set to all applications that are using it and keeping the data set closed for long periods while the data set is rebuilt.

There are customers who cannot take the application off-line for any amount of time and these customers have been asking for a tool to reclaim this empty space.

The disclosed invention takes advantage of the function of CA Reclaim to provide a new method to reclaim the existing empty CAs of the VSAM KSDS data set without requiring that the data set be taken off-line or closing the data set. The invention involves creating a new VSAM r...