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Systematic approach to identifying underlying issues in processes systems and operations

EXHST - Exhaust

Enhanced Definition

In mainframe computing, "exhaust" (often abbreviated as `EXHST` in custom contexts) refers to the complete processing or consumption of a finite data source, such as a file, queue, or log, until no further items remain. It can also describe the state where a system resource has been fully utilized or depleted, reaching its capacity limit.

Key Characteristics

- Completeness: Implies that all available items from a specified source have been processed, read, or consumed entirely.
- Finite Source: Typically applies to resources or data sets with a defined beginning and end, such as sequential files, VSAM files, message queues (e.g., MQSeries, CICS Temporary Storage), or system logs (e.g., SMF, SYSLOG).
- State Indication: Can denote a condition where a critical system resource (e.g., memory, CPU cycles, disk space, I/O channels, buffer pools) has reached its maximum capacity or is fully utilized.
- Programmatic Detection: Often detected programmatically within applications, for example, by an AT END condition in COBOL when reading a file, or an empty queue status returned by a messaging API.
- Resource Management Context: In the context of resource exhaustion, it signals a need for system administrators to intervene, such as increasing capacity, optimizing resource allocation, or tuning system parameters.

Use Cases

- Batch File Processing: A COBOL batch program reading a sequential input file (e.g., a flat file on DASD or tape) until an AT END condition is met, signifying that all records have been processed.
- Message Queue Draining: A CICS transaction or a batch program continuously retrieving and processing messages from an IBM MQSeries queue until the queue is empty, ensuring all pending work is handled.
- Log File Analysis: A utility program or a custom job reading and processing every record from a system log (e.g., SMF data, SYSLOG) from start to finish for auditing, reporting, or performance analysis