JES3

Job Entry Subsystem 3

Please! Verify all details or suggestions with the appropriate vendor and / or vendor's manuals.

The work environment for JES3 consists of processors and I/O devices. JES3 covers a range of data processing needs, partly because it can accommodate various combinations of processors and devices. JES3 is a manager of its environment, so if you understand that environment, it will be easier for you to understand JES3.
This topic describes the I/O devices used by JES3 and MVS and the following environments in which JES3 runs:

Single-processor environment
Multiprocessor environment
Remote job processing environment
JES3 networking environment
APPC environment

A JES3 complex can involve any combination of these environments.

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You might choose to enable JES3 as an alternative to the base JES2 element. It also accepts the submission of work for the BCP. Major JES3 functions and design features include:
The interpretation of job control language (JCL) statements

The disposition of output
A single system image
Workload balancing
Deadline scheduling
Dependent job control
Control flexibility

JES3 website

The JES3 Library

SA22-7540-10 Commands PDF

SA22-7542-09 Customization PDF

N/A Data Areas Vol 1 (IATYADA-IATYLCA) PDF

N/A Data Areas Vol 2 (IATYLCP-IATYSTT) PDF

N/A Data Areas Vol 3 (IATYSUP-IATY8FB) PDF

GA22-7548-09 Diagnosis Reference PDF

GA22-7547-09 Diagnosis PDF

SA22-7549-09 Initialization and Tuning Guide PDF

SA22-7550-09 Initialization and Tuning Reference PDF

SA22-7551-06 Introduction PDF

SA22-7552-10 Messages PDF

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JES2 compared to JES3

z/OS concepts
IBM^® provides two kinds of job entry subsystems: JES2 and JES3. In many cases, JES2 and JES3 perform similar functions, but most installations use JES2.
Both JES2 and JES3 read jobs into the system, convert them to internal machine-readable form, select them for processing, process their output, and purge them from the system.
Some principle differences between the two JES systems include:

In a mainframe installation that has only one processor, JES3 provides tape setup, dependent job control, and deadline scheduling for users of the system, while JES2 in the same system would require its users to manage these activities through other means. In an installation with a multiprocessor configuration, there are noticeable differences between the two, mainly in how JES2 exercises independent control over its job processing functions. That is, within the configuration, each JES2 processor controls its own job input, job scheduling, and job output processing.

In cases where multiple z/OS^® systems are clustered (a sysplex), it is possible to configure JES2 to share spool and checkpoint data sets with other JES2 systems in the same sysplex. This configuration is called Multi-Access Spool (MAS). In contrast, JES3 exercises centralized control over its processing functions through a single global JES3 processor. This global processor provides all job selection, scheduling, and device allocation functions for all of the other JES3 systems.
With JES3, installations may decide whether the global JES3 or z/OS base control program will handle device allocation. With JES2, only the z/OS base control program handles device allocation.

JES3 differs from JES2 in two main processing areas:

JES3 exercises centralized control over its job processing functions. JES2 exercises independent control. With JES3, a single, global processor controls job, device, and workflow for all processors in a multi-processor environment.
JES3 does pre-execution of job setup. JES2 does not do this.

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Go to the JES2 page

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