Browse Prior Art Database

Exclusive Record Control on Direct Access Data Sets

IP.com Disclosure Number: IPCOM000078007D
Original Publication Date: 1972-Oct-01
Included in the Prior Art Database: 2005-Feb-25
Document File: 2 page(s) / 20K

Publishing Venue

IBM

Related People

Frazer, DK: AUTHOR [+2]

Abstract

With the addition of one byte to the data portion of all data set records, an access method, hence a user, can obtain exclusive control of a single record within the data set. By resolving exclusive control to a single record, multiple users can be allowed access to the same data set.

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Exclusive Record Control on Direct Access Data Sets

With the addition of one byte to the data portion of all data set records, an access method, hence a user, can obtain exclusive control of a single record within the data set. By resolving exclusive control to a single record, multiple users can be allowed access to the same data set.

The additional byte is used to indicate exclusive control status. The access method requiring exclusive control reads the record and sets the indicator with the following uninterruptible channel program for exclusive read:

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The indicator byte in the read buffer is then checked and if not set to exclusive control, the access method now has the record exclusively. If the byte does indicate exclusive control, the record was under exclusive control prior to the current request and the access method notifies the requestor (perhaps itself or index updates) and/or queues the request.

The user must notify the access method when exclusive control is no longer needed, whereupon the record is rewritten with the indicator showing the record as being available.

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