IEFJOBS

Enhanced Definition

`IEFJOBS` is a z/OS system service (provided as a macro) that allows authorized programs to retrieve detailed information about jobs currently active, waiting, or in the output queue within the system. It provides a programmatic interface to access various job -related attributes and status details managed by the Job Entry Subsystem (JES).

Key Characteristics

- System Macro: It is invoked via an assembler macro call (e.g., IEFJOBS GET_JOB_INFO) within an authorized program, enabling direct interaction with system components.
- Authorized Use Only: Requires the calling program to be running in supervisor state, a privileged program key (typically 0-7), or be APF-authorized to ensure system integrity and security.
- Accesses JES Data: Retrieves job information directly from JES2 or JES3 internal control blocks, such as Job Queue Elements (JQEs), Job Control Blocks (JCBs), and other related data structures.
- Provides Diverse Information: Can return a wide array of details including job name, job ID, current status (e.g., executing, waiting for initiator, output hold), priority, initiator name, CPU time used, and resource consumption.
- Synchronous Operation: Typically operates synchronously, meaning the calling program waits for the IEFJOBS service to complete and return the requested information directly into a specified buffer.

Use Cases

- System Monitoring and Performance Tools: Utilities like SDSF or third-party monitoring products use IEFJOBS to gather real-time data on active jobs, their status, and resource consumption for display and analysis.
- Job Scheduling and Management Systems: Automated job schedulers leverage IEFJOBS to verify job status, check for job dependencies, manage job queues programmatically, and make dynamic scheduling decisions.
- Custom Automation and Utilities: System programmers write REXX or assembler programs that utilize IEFJOBS to automate tasks based on job states, such as alerting operators to long-running jobs or performing actions on jobs in specific queues.
- Security and Audit Utilities: Programs needing to track which jobs are running under specific user IDs, resource groups, or with particular attributes can use IEFJOBS to extract this information for auditing purposes.

Related Concepts

IEFJOBS is fundamentally tied to the Job Entry Subsystem (JES2/JES3), serving as a controlled interface to the internal job -related control blocks and data structures that JES manages. It operates at a lower level than typical JCL or operator commands, directly interacting with the z/OS Supervisor and requiring authorized program status (often via an APF-authorized library or a Supervisor Call (SVC)). It complements other system services like IEFACTRT (SMF exit for job termination) and IEFSSREQ (subsystem interface) by focusing specifically on retrieving *active* or *queued* job status rather than job initiation or termination events. It provides the raw data that higher-level utilities like SDSF then format and display.

Best Practices:

Minimize Calls: Due to the overhead involved in accessing and processing system control blocks, use IEFJOBS calls judiciously and avoid excessive or frequent polling if less critical information is needed.
Robust Error Handling: Always include comprehensive error checking for the return codes and reason codes provided by the IEFJOBS macro to properly handle scenarios such as job not found, insufficient authorization, or internal system errors.
Proper Authorization: Ensure that any program utilizing IEFJOBS is correctly authorized (e.g., APF -authorized, running in supervisor state, or having a suitable program key) to prevent security violations, abends, and ensure successful execution.
Buffer Management: Allocate sufficient and appropriately aligned storage for the output buffer to prevent storage overlays or abends when retrieving potentially large amounts of job information.
Consult IBM Documentation: Always refer to the latest IBM z/OS MVS Programming: Authorized Assembler Services Guide and z/OS MVS Data Areas for precise syntax, parameter details, and control block layouts, as these can evolve across z/OS versions.