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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Any reference to an IBM product, program, or service is not intended to state iitialization imply that only that IBM product, program, or service may be used.

In effect, spooling is a near-synonym for queueing. This time is primarily a function of the amount of time to do DASD reads and writes of the checkpoint data set information. The idea for this post came from a suggestion by Ian Watson. Scalability If you have many active MAS members and large batch processing overheads, it is best to understand the watermarks of JES2 scalability.

On the other hand, with a initializationn cycle time, JES2 appears to be much faster. Just because one member is unable guiee access the queues another member might be performing useful work.

z/OS JES2 Initialization and Tuning Reference

You can then analyze the trace information that is in the dump. Therefore, there is a direct correlation between the specification for HOLD and the amount of useful time. By fencing volumes, you can improve JES2 performance. JES2 uses more processor cycles. This is especially useful for intermittent performance issues where the environment might go for hours without seeing a problem.

If the HOLD parameter is set lower than the time it takes for the primary write to 2 JES2 Performance and Availability Considerations complete, the nad time is extended until the primary write completes. TSO submit, cancel, and status commands are slow. Consult your local IBM representative for information on the products and services currently available in your area. In this instance, WLM takes no action on the image in question.

Many JES2 processes involve updating checkpoint annd blocks, then writing data to spool, and then making final updates to checkpoint control blocks. The LOCKOUT parameter reflects the time between initializatiom member being denied access to the shared queues and the time the controlling member is assumed to be down.


However, there is no inirialization to know for sure the details of how classes are set up at your particular site unless you ask about it. Start high, and guode lower it if there are problems and you do not see the messages when you wanted to.

Sample JES2 initialization data set

Those paper towels on that roll in the kitchen are queued up waiting for you to use each one in turn, just like a report waiting to be printed or a set of JCL statements waiting for its turn to run. In reality, the HOLD parameter is a minimum hold value. WLM attempts to distribute the initiators across all members in the sysplex to balance the use of the systems while taking care that jobs with affinities to specific systems are not hurt by WLM decisions.

This technology assists the checkpoint useful time. 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.

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 when a checkpoint data set resides on DASD.

However, contention-driven access has the disadvantage of causing potential member lockout and severe member degradation in an MAS environment. This paper concentrates on this method of checkpoint access. An external writer is a program that reads and processes sysout files, and such a program can route the output to any available destination.

CHANGES “z/OS V1R JES2 Initialization and Tuning Guide” IBM Library Server

Optimizing response time This approach is for installations where some JES2 functions have a need of a response time smaller than the cycle time. From the perspective of a single member in a complex, checkpoint-related useful time is the time in a checkpoint cycle, which starts at the beginning of the primary write and ends at the beginning of the final write.

The most obvious example of this situation is a printer. It facilitates the split of a large DASD spool pool into smaller pools for critical systems. Both types of initiators can coexist. The primary write operation is used to bring the down level DASD copy of the queues up to date. On very early mainframe computers, the system read input jobs from a punched card reader, one line at a time, one line from each punched card. Questions on the capabilities of non-IBM products should be addressed to the suppliers of those products.


IBM z/OS JES2 Initialization and Tuning Reference (SA)

Remote job entry lines time out. You also have the option to turn on tracing without the trace logging function using the following command: The imagery of spooling was probably taken from processes that wind some material such as thread, string, fabric or gift wrapping paper onto a spindle initializatipn spool.

IBM, therefore, cannot guarantee or imply reliability, serviceability, or function of these programs. In essence, running these traces does not have any significant overhead to the operation of JES2.

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. This information contains examples of data and reports used in daily business operations.

By allowing the use of relative track addressing, JES2 can support a spool data set of up to 64 KB tracks in size, anywhere on a volume. This information also includes a summary table of the JES2 initialization statements and their primary parameters. Who should read this information This information is intended for JES2 system programmers or for anyone responsible for initializing or tuning JES2. This portion of the cycle then updates the storage queues of the system that is holding the checkpoint.

JES2 is still a single extent data set and has a very low read-to-write ratio. Bottlenecks, it might be said.

There is no significant performance overhead to JES2 itself, and it will avoid the operational use of the JES2 checkpoint reconfiguration dialog. The current spool addressing scheme uses an absolute track address. The following points characterize symptomatic evidence of a JES2 performance issue: 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.