Initialization statements

In a shared DASD environment, an event reader subtask started at the controller reads the events from the event data set. The events are then used to update the current plan. A sequence number, specified on the ERSEQNO of the ERDROPTS initialization statement, identifies each event reader subtask. This number is used to build a DD name in the JCL procedure of the address space where the event reader is started. This DD name identifies the event data set that the event reader should process. It has the format EQQEVDnn, where nn is the sequence number of the event reader that services this event data set.

When a tracker has a non-DASD connection with the controller (that is, an XCF, NCF, or TCP/IP connection) or the tracker and controller are running in the same address space, the event writer can be used to forward events directly to the controller.

When an event writer is started with the EWSEQNO keyword on the EWTROPTS initialization statement, the event writer logs event information on the event data set and adds the event concurrently to the data router queue. The event is not read back from the event data set each time as it is by an event reader subtask. In this configuration, events are only read back from DASD if they need to be resent to the controller during restart processing, for example when the communication link to the controller becomes active after an outage.

For more information about the ERDROPTS and EWTROPTS initialization statements, see ERDROPTS and EWTROPTS. For detailed information about allocating event data sets, see also Event data sets (EQQEVDS, EQQEVDnn, and EQQHTTP0).