Event data sets (EQQEVDS, EQQEVDnn, and EQQHTTP0)

Every HCL Workload Automation for Z address space requires a unique event data set. The data set is device-dependent and must have only a primary space allocation. Do NOT allocate any secondary space. The data set is formatted the first time it is used. Each time you use the data set, HCL Workload Automation for Z keeps a record of where to start. When the last track of the data set is written, HCL Workload Automation for Z starts writing on the first track again.

The data set contains records that describe events created by HCL Workload Automation for Z job-tracking functions. An event-writer task writes to this data set; an event-reader task reads from it. The job-submit task also uses the event data set to checkpoint its activities, using the first record in the data set (the header record). The submit task in a controller address space takes these checkpoints when the computer workstation is the same system (the workstation destination is blank), so the address space needs the EQQEVDS event data set allocated even if there is no event writer task. When an event writer task is started in the controller address space, it shares the data set with the submit task.

Because the event data set provides a record of each event, events will not be lost if an event-processing component of HCL Workload Automation for Z must be restarted. The submit checkpointing process ensures that submit requests are synchronized with the controller, thereby preventing lost requests caused by communication failures.

Define enough space for a single extent data set so that it does not wrap around and write over itself before an event is processed. Two cylinders are enough at most installations. The space allocation must be at least 2 tracks when the record length is 100. There must be sufficient space in the event data set to accommodate 100 records. Consider this requirement if you will define the event data set with a record length greater than 100. For example if you define an LRECL of 15 000, the minimum space allocation is 34 tracks, which equates to 102 records and an event data set that would wrap around very quickly in most installations.

To aid performance, place the event data set on a device that has low activity. If you run programs that use the RESERVE macro, try to allocate the event data set on a device that is not reserved or where only short reserves are taken. The reserve period must be less than 5 minutes.

If you use the job log retrieval function, consider allocating the event data set with a greater LRECL value than that in HCL Workload Automation for Z non-VSAM data sets. This improves performance because input/output (I/O) operations will be reduced because fewer continuation (type NN) events will be created. You can specify 0, or a value from 100 to 32 000 bytes for LRECL. Any other value will cause the event writer to end, and message EQQW053E will be written to the message log. If you do not specify a value for LRECL or specify 0, the data set will be forced to have an LRECL of 100 when it is opened by HCL Workload Automation for Z. However, the data set must be unblocked: the block size must be equal to the logical record length. If you intend to activate job log retrieval function, use one of the these formulas to estimate the LRECL that you should specify:

In the first formula, NN is the number of continuation events, and EV is the number of all other events. Event types are found in position 21 of the event records. In the second formula, N is the average number of NN events per job. If your calculation yields a value of less than 110, there will be little or no improvement in performance. In this case, you should specify an LRECL value of 100.

You will probably need to test your system first to get an idea of the number and event types that are created. You can then reallocate the event data set when you have gathered information about the events created at your installation. But, before you reallocate an event data set, ensure that the current plan is completely up-to-date. You must also stop the event writer, and any event reader, that uses the data set.