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Incarnation - Instance

Enhanced Definition

An **instance** in the mainframe context refers to a specific, independent execution or occurrence of a program, transaction, or resource within the z/OS environment. It represents a unique, dynamic manifestation of a static entity. The term "incarnation" is sometimes used less formally as a synonym, particularly when referring to a specific *run* or *manifestation* of a job or process.

Key Characteristics

- Uniqueness: Each instance operates independently, maintaining its own state, data, and execution context, distinct from other instances of the same underlying program or resource.
- Resource Allocation: Instances typically acquire and release dedicated resources (e.g., memory, CPU cycles, I/O buffers, file handles) for their duration, managed by the z/OS operating system.
- Lifecycle: An instance has a distinct lifecycle, from initiation (e.g., job submission, transaction start, resource allocation) to termination (e.g., job completion, transaction end, resource deallocation).
- Concurrency: Multiple instances of the same program or transaction can often execute concurrently, requiring the underlying code to be designed for reentrancy or serial reusability to ensure data integrity and efficiency.
- Isolation: Instances are generally isolated from each other at the operating system level to prevent interference, though they may share common data or resources under controlled
The term "Inch - Unit of measure" as a standard unit of length does not have a specific, unique, or technical definition, usage, or relevance within the IBM mainframe (z/OS, COBOL, JCL, CICS, DB2, IMS) ecosystem that would warrant a dedicated glossary entry.
Mainframe technologies primarily deal with logical and physical data structures, processing units, memory, I/O operations, and software constructs, which are measured in terms of bytes, blocks, tracks, cylinders, CPU cycles, milliseconds, etc. Physical dimensions of hardware components (like the size of a server rack or a tape cartridge) might be expressed in inches, but this is a general physical measurement applicable to any hardware, not a concept intrinsic or specific to mainframe *software*, *architecture*, or *programming* as defined by your glossary's focus.
Therefore, generating a glossary entry for "Inch" in the context of z/OS, COBOL, or JCL would be misleading as it does not possess a specialized mainframe-specific meaning or application.