Abstract for JES2 Initialization and Tuning Guide · How to send your comments to IBM · Summary How to initialize JES2 in a multi-access SPOOL configuration. JES2 Initialization and Tuning Guide. z/OS JES2 Initialization and Tuning Guide contains the following information in support of JES2 Email Delivery Services. JES2 initialization statement and parameter summary tables · JES2 initialization statement descriptions · APPL(jxxxxxxx) – Application Characteristics.

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Example 2 uses the output from Example 1. To do so, you can use the following command: You also have the option to turn on tracing without the trace logging function using the following command: The idea for this post came from a suggestion by Ian Watson. In essence, running these traces does not have any significant overhead to the operation of JES2.

The checkpoint mechanism is as follows: Spool partitioning Spool partitioning or fencing allows track group allocation across explicit volumes. Therefore, overall useful time for the complex should be appreciably higher than a single member in the MAS. So, short holds of, say, 0 to 10 can cause various JES2 Performance and Availability Considerations 5 processes to take too long to complete too much checkpoint thrashing.

Many sysout files are never really printed, but are viewed and further processed directly from the spool space under TSO using a software product like SDSF. This information also includes a summary table of the JES2 initialization statements and their primary parameters. To ensure spool space is not wasted, performance is not degraded, and sufficient spool space is catered for, take care with the following parameters of SPOOLDEF: Checkpoint-related useful work should not be confused with JES2 work.


Such jobs can receive space from more volumes than if the job spends its life on a single system. If it must take two cycles, then it can take two or more seconds to complete and can write twice as much data to the checkpoint. Specifically, JES2 supports both relative and absolute track addressing for spool.


If both checkpoints reside on coupling facilities that become volatile a condition where, if power to the coupling facility device is lost, the data is lostyour data is less secure than tunig a checkpoint data set resides on DASD. This paper concentrates on this method of checkpoint access.

Any references in this information to non-IBM Web sites are provided for convenience only and do not in any tnuing serve as an endorsement of those Web sites.

This data should be compared for tunng systems to establish which member has the most activity.

Remote initializatiin entry lines time out. When using this command to display information pertaining to a large range of jobs, started tasks or TSO users. These values should be re-evaluated if the JES2 workload is not distributed homogeneously across all the members of the MAS. With multiple spool devices, they should target different channels and control units on separate channels. The limit on the number of job queue elements JQEs is These limits define the tuniing number of each element that can be active in the MAS at any one time.

Processes within JES2 which do not need to access the checkpoint will run uninterrupted even during a time frame when the checkpoint is in a non-useful state. When using any of the other traces, you must analyze the raw formatted data to determine what is occurring. A starting recommendation is to make this 2 to 3 times the desired cycle time or split the difference and do 2. Commands such as these should be broken up into ranges, such as: These parameters directly affect the amount of time a system can use to make updates to the queues.

There are no hard and fast recommendations to follow.

Consequently, concurrent read and write activity are constantly requested to the spool data sets. When operating in a MAS, note that you should summarize the statistics to give the complete picture. JES2 Performance and Availability Considerations 19 Because the primary concern is performance issues, the number of requests, the source address space, and the time to complete the requests are usually the first indicators of a problem.

After JES2 reads a job into the system, JES2 writes the job, its job control language, its control statements, and its data to a spool data set until further processing can occur.


JES2 Performance and Availability Considerations 3 There are two methods of operating a multi-access spool MAS configuration to provide individual members access to the checkpoint data set: You can change the value dynamically using an operator command or the online SDSF interface.

We do not recommend placing both checkpoints on coupling facility structures or placing the primary checkpoint on DASD and the secondary checkpoint on a coupling facility structure.

IBM z/OS MVS mainframe overview of JES2

Complex useful time During a checkpoint cycle it is important to ensure that some member of the complex is using it. Some small development company might have just one job class for everything. The following paragraph does not apply to the United Kingdom or any other country where such provisions are inconsistent with local law: This can realize performance improvements inigialization sysout intensive batch jobs.

If it is done in one checkpoint cycle, the process takes less than a second and less data is written to the checkpoint.

Abstract for JES2 Initialization and Tuning Reference

The limit on the number of job output elements JOEs is The Usermod will require a JES2 cold start. You may copy, modify, and distribute these sample programs in any form without payment to IBM, for the purposes of developing, using, marketing or distributing application programs conforming to the application programming interface for the operating platform for which the sample programs are written.

This adjustment has instant effect and reflects real-time values as opposed to an average over a stated period. This information describes JES2 initialization statements and their parameters and provides summary charts that highlight details of the statements.

Only low-usage data sets if any should be allocated on the same volume as the checkpoint data set.