IMS Spool API performance considerations

The IMS Spool API interface uses z/OS® services within an IMS application while minimizing the performance impact of the z/OS services on the other IMS transactions and services.

For this reason, the IMS Spool API support places the print data directly on the JES spool at insert time instead of using the IMS message queue for intermediate storage. The processing of IMS Spool API requests is performed under the TCB of the dependent region to ensure maximum usage of N-way processors. This design reduces the error recovery and JES job orientation problems.