Trigger count

You must set a nonzero value for the Trigger Count option to specify a number of I/O or fetch requests against the trigger. When the count of I/O or fetch requests reaches the number you specify, AR/CTL issues an automatic checkpoint request.

How the Trigger Count option works depends on whether the trigger is an input file, an output file, a Db2 cursor, or an IMS PCB:

• If the application program uses a trigger file for input, AR/CTL issues the automatic checkpoint just before the read for the specified number plus one. For example, if you set the option to perform an automatic checkpoint for the input trigger file every ten records, when the program issues the read for the eleventh record AR/CTL issues an automatic checkpoint request. Ten input records make up the logical unit of work.
• If the application program uses a trigger file for output, AR/CTL issues the automatic checkpoint just after the write for the specified number. For example, if you set the option to perform an automatic checkpoint for the output trigger file every ten records, when the program issues the write for the tenth record AR/CTL issues an automatic checkpoint request after the tenth record is written. Ten output records make up the logical unit of work.
• If the application program uses a trigger cursor, AR/CTL issues the automatic checkpoint just before the fetch for the specified number plus one. For example, if you set the option to perform an automatic checkpoint for the trigger cursor every ten fetches, when the program issues the fetch for the eleventh row AR/CTL issues an automatic checkpoint request. Ten rows make up the logical unit of work.
• If the application program uses a trigger PCB, AR/CTL issues the automatic checkpoint when the count of I/O requests against this PCB reaches the value you specify with the Trigger Count option and a root boundary is crossed. The checkpoint is issued just before a GET -type call that uses this PCB. For example, if you set the option to perform an automatic checkpoint every ten calls that use the trigger PCB and if the tenth call is a GN call that crosses a root boundary, AR/CTL issues an automatic checkpoint request before the GN call is processed. For ISRT calls against a GSAM PCB, AR/CTL issues the automatic checkpoint after the call.