Interval

Enhanced Definition

An interval, in the context of IBM mainframe systems, refers to a specific, measurable duration of time used to control, schedule, monitor, or report on activities within z/OS and its associated subsystems. It defines a fixed or variable period for an action to occur, a delay to be observed, or data to be collected, playing a crucial role in system management and performance.

Key Characteristics

- Measurable Duration: Always represents a quantifiable amount of time, typically expressed in seconds, minutes, or hours, depending on the context and subsystem.
- System-Wide Application: Utilized across various z/OS components, including CICS, DB2, IMS, System Measurement Facility (SMF), and Resource Measurement Facility (RMF), for diverse operational purposes.
- Configurable: Often specified as a parameter in system definitions (e.g., IEASYSxx), JCL, program commands (e.g., EXEC CICS), or monitoring tool settings, allowing administrators to tailor system behavior.
- Event-Driven or Periodic: Can trigger an event after a specified delay (e.g., CICS DELAY) or define the frequency of recurring actions (e.g., SMF data collection, RMF monitoring cycles).
- Performance and Resource Management: Crucial for managing system performance, optimizing resource allocation, and ensuring timely execution of tasks and utilities.
- Monitoring and Reporting Basis: Forms the fundamental unit for collecting performance metrics and generating operational reports at regular frequencies, enabling trend analysis and problem diagnosis.

Use Cases

- CICS Transaction Scheduling and Delay: Using EXEC CICS START TRANSID(...) INTERVAL(...) to initiate a transaction after a specified delay, or EXEC CICS DELAY INTERVAL(...) to pause a program's execution for a defined period.
- System Measurement Facility (SMF) Data Collection: Defining the frequency (e.g., every 15 or 30 minutes) at which SMF writes performance, accounting, and security data to its datasets,