DEFINE

Creating or Specifying

Enhanced Definition

In the context of IBM z/OS, `DEFINE` refers to the process of formally creating, allocating, and specifying the attributes and characteristics of a resource, such as a dataset, database object, or system component, so that the operating system and associated subsystems can recognize, manage, and utilize it. This action makes the resource available for use within the mainframe environment.

Key Characteristics

- Resource Allocation: Often involves reserving storage space on direct access storage devices (DASD) or specifying logical structures for database objects.
- Attribute Specification: Requires setting various parameters like record format (RECFM), block size (BLKSIZE), dataset organization (DSORG), access method (AM), security profiles, or database schema details.
- System Catalog Integration: Most defined resources, especially datasets, are registered in the z/OS system catalog or subsystem-specific catalogs (e.g., DB2 catalog) for easy retrieval and management.
- Tool-Specific Syntax: The exact syntax and utility used for definition vary depending on the resource type (e.g., IDCAMS for VSAM, JCL DD statements for non-VSAM, DDL for DB2, RDO for CICS).
- Persistence: Once defined, a resource persists across system re-IPLs until it is explicitly deleted or undefined.

Use Cases

- Defining VSAM Datasets: Using the IDCAMS DEFINE CLUSTER command in JCL to create Key-Sequenced Data Sets (KSDS), Entry-Sequenced Data Sets (ESDS), or Relative Record Data Sets (RRDS).
- **Defining DB2 Database