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Data Recovery for CICS Using Time Stamps

IP.com Disclosure Number: IPCOM000044059D
Original Publication Date: 1984-Oct-01
Included in the Prior Art Database: 2005-Feb-05
Document File: 2 page(s) / 34K

Publishing Venue

IBM

Related People

Meacock, G: AUTHOR

Abstract

In the IBM database, data communication program product Customer Information Control System (CICS) queues may occupy more than one control interval. Each control interval starts with three identifiers: firstly, a queue name; secondly, a pointer for chaining which, when non-zero, points to another control interval containing a succeeding portion of the queue (chaining); and, thirdly, a sequential time stamp. If a crash occurs, CICS is restarted and the recovery routine gives the pointer to the first control interval containing the queue being processed before the crash, enabling this control interval to be read. If the pointer is non-zero, the second control interval is read and CICS checks that the queue names are the same.

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Data Recovery for CICS Using Time Stamps

In the IBM database, data communication program product Customer Information Control System (CICS) queues may occupy more than one control interval. Each control interval starts with three identifiers: firstly, a queue name; secondly, a pointer for chaining which, when non-zero, points to another control interval containing a succeeding portion of the queue (chaining); and, thirdly, a sequential time stamp. If a crash occurs, CICS is restarted and the recovery routine gives the pointer to the first control interval containing the queue being processed before the crash, enabling this control interval to be read. If the pointer is non-zero, the second control interval is read and CICS checks that the queue names are the same. Then CICS checks that the time stamp of the second control interval is greater than the time stamp of the first control interval. In a CICS environment this use of time stamps provides increased efficiency. CICS intra-partition transient data allows application programs to add records to and remove records from queues that are managed in a FIFO (first-in, first-out) manner. The records for each queue are held in a series of control intervals on a VSAM data set, as shown in Figs. 1 and 2, where chaining between control intervals is indicated by an arrow and determined by a pointer. While the CICS system is operational, the first and last control intervals (and so any intermediate control intervals) for each queue are known. The problem occurs when the CICS system crashes and is subsequently restarted, for then only the first control interval for each queue may be known. The last control interval (and any intermediate control intervals)...