Edit

Enhanced Definition

In the context of IBM z/OS, "Edit" refers to the interactive process of modifying the content of datasets, typically members within Partitioned Datasets (PDS or PDSE) or sequential datasets. It is a fundamental operation for developers and system administrators to update source code, JCL, configuration files, or data records. In the mainframe context, 'edit' refers to the process of modifying existing data, program source code, JCL, or configuration files stored on z/OS datasets or within specific mainframe subsystems. It involves making changes to the content of a file or member, ranging from simple text corrections to complex structural alterations.

Key Characteristics

- Interactive Operation: Primarily performed interactively via a 3270 terminal emulator, often within the ISPF (Interactive System Productivity Facility) environment.
- Dataset-Oriented: Operates directly on members of PDS/PDSEs (e.g., COBOL programs, JCL procedures) or entire sequential datasets.
- Full-Screen Editors: Utilizes full-screen editors like ISPF Edit (the most common on z/OS) or XEDIT on VM, providing a visual interface for content manipulation.
- Line Commands: Supports a rich set of line commands (e.g., C for copy, M for move, D for delete, I for insert) for efficient manipulation of lines of text.
- Primary Commands: Offers primary commands (e.g., SAVE, CANCEL, FIND, CHANGE, CUT, PASTE) for broader operations across the entire dataset or member.
- Session-Based: Changes are typically held in an edit buffer during an active session and are only permanently written to the dataset upon a SAVE command.

Use Cases

- Developing and Maintaining Programs: Modifying COBOL, PL/I, Assembler, or REXX source code members stored in PDS/PDSE libraries.
- Updating JCL Procedures: Editing JCL (Job Control Language) members to define job steps, allocate datasets, and specify program execution parameters.
- Configuring System Parameters: Changing system-level configuration files, such as PARMLIB members, to adjust z/OS behavior or subsystem settings.
- Correcting Data Records: Viewing and making direct corrections to records within sequential datasets or, less commonly, VSAM files, often for data integrity or testing purposes.
- Creating New Artifacts: Generating new program members, JCL procedures, or data files from scratch within a specified dataset.

Related Concepts

Edit is intrinsically linked to ISPF, which provides the primary interactive interface for editing on z/OS. It operates on PDS/PDSEs, the standard dataset types for storing editable members like COBOL programs and JCL. Modern Source Code Management (SCM) systems (e.g., Endevor, CA-Librarian) integrate with ISPF Edit, providing version control, check-out/check-in mechanisms, and change tracking, thereby enhancing the editing workflow. The underlying TSO/E (Time Sharing Option/Extensions) environment provides the interactive capabilities that ISPF and its editor leverage.

Best Practices:

Utilize SCM: Always perform edits on source code and critical JCL members through a robust Source Code Management system to ensure version control, audit trails, and concurrent development.
Backup Before Major Changes: For non-SCM managed files, create a backup copy of a member or dataset before undertaking significant or potentially risky edits.
Master Editor Commands: Learn and effectively use ISPF Edit line and primary commands to maximize efficiency and productivity during editing sessions.
Test Changes Thoroughly: After editing, always compile, link-edit, and thoroughly test any modified source code or JCL to prevent introducing errors into production.
Use Edit Profiles: Configure and leverage ISPF Edit profiles for features like syntax highlighting, auto-numbering, auto-save, and tailored tab settings to improve readability and consistency.