PRTY Parameter

Purpose

The PRTY parameter in JCL specifies the selection priority for a job within its job class. It influences the order in which jobs are selected for execution when multiple jobs are waiting in the same job class queue. Higher values indicate higher priority.

Syntax

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//jobname JOB (accounting-information),programmer-name,PRTY=priority

Format

• PRTY is a keyword parameter on the JOB statement
• priority: A numeric value between 0 and 15 (for JES2 systems)
• JES3 systems may use different ranges (typically 0-14)
• Higher values indicate higher priority
• Default priority is installation-defined, often based on job class

Examples

Basic Usage

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//PAYROLL JOB (ACCT123),'JOHN SMITH',PRTY=12

Assigns priority level 12 to the job

With Multiple Parameters

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2
//REPORT  JOB (ACCT456),'JANE DOE',
//             CLASS=A,PRTY=8,MSGCLASS=X

Assigns priority level 8 to the job in CLASS A

Low Priority Job

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//BACKUP  JOB (ACCT789),'OPS TEAM',CLASS=B,PRTY=3

Assigns low priority (3) to a backup job, allowing other jobs to run first

High Priority Job

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//URGENT  JOB (ACCT321),'PROD SUPPORT',CLASS=A,PRTY=15

Assigns highest priority (15) to an urgent job

Priority Levels and Typical Usage

Note: Actual usage varies by installation

System Considerations

• PRTY affects job selection order, not execution priority once running
• Jobs are selected for execution within a job class by priority
• Jobs with equal priority are typically selected in FIFO order (first in, first out)
• Installation-defined algorithms may modify the default priority
• JES2 and JES3 handle priorities differently:
  • JES2: Priority values range from 0 to 15
  • JES3: Priority values typically range from 0 to 14
  • Different installations may customize these ranges
• Actual priority of a job may be influenced by other factors:
  • Workload Manager (WLM) policies
  • Service class assignments
  • Performance groups
  • Time of day
  • System load

Priority Determination

The actual priority used for job selection may be influenced by several factors:

1. PRTY value specified in the JOB statement
2. Default priority assigned to the job class
3. Installation-defined algorithms that may adjust priority based on:
   • Time of day
   • Total job run time
   • Job size (memory or I/O requirements)
   • User or group identifier
   • Account code
4. Operator commands that can change job priority dynamically

Notes

• PRTY is optional - if omitted, a default priority is assigned
• Default priority is often based on the job class
• PRTY affects job selection, not CPU dispatching priority during execution
• Jobs with higher PRTY values are selected before jobs with lower values in the same class
• Some installations may restrict the PRTY values users can specify
• Operators can change the priority of a job using JES commands
• Excessive use of high priorities can negate the effectiveness of the priority system
• In modern z/OS environments, WLM may have more influence than PRTY on job selection

Common Mistakes

• Using a higher priority than necessary, causing resource contention
• Using high priorities for all jobs, defeating the purpose of prioritization
• Assuming PRTY affects execution performance (it only affects selection order)
• Requesting unauthorized priority levels (some installations restrict high values)
• Confusing PRTY with CLASS (they serve different purposes)
• Not considering the impact of WLM policies on job scheduling

Related Concepts

• JOB Statement - Contains the PRTY parameter
• CLASS Parameter - Job class, which works with PRTY to determine selection order
• TIME Parameter - Specifies maximum run time, which may influence priority calculations
• SCHENV Parameter - WLM scheduling environment, which may override PRTY in selection
• SYSAFF Parameter - System affinity, which restricts which systems can run the job

Related Pages

• JOB Statement
• CLASS Parameter
• TIME Parameter
• REGION Parameter
• SCHENV Parameter