Action Code - Processing instruction indicator
An action code is a single character or a short alphanumeric string entered by a user or program to instruct an application on a specific operation to perform on data, often within an interactive mainframe transaction or utility. It acts as a concise command to trigger predefined processing logic, guiding the application's flow.
Key Characteristics
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- Conciseness: Typically a single character (e.g.,
S,U,D) or a very short string, designed for quick input. - Application-Specific: The meaning and behavior of an action code are defined entirely by the application program; there is no universal standard across all mainframe systems.
- User-Driven: Frequently used in screen-based online transaction processing (OLTP) applications (like CICS or IMS TM) to allow end-users to select options or manipulate records.
- Programmatic Interpretation: The application program reads the action code from the input buffer and uses conditional logic (e.g.,
IFstatements in COBOL) to branch to the appropriate processing routine. - Validation: Action codes are almost always subject to validation by the application to ensure they are valid for the current screen, data, and user's authorization.
- Efficiency: Provides a rapid and direct method for users to interact with data or functions without navigating extensive menus or entering lengthy commands.
- Conciseness: Typically a single character (e.g.,
Use Cases
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- Online Transaction Processing (CICS/IMS TM): In a CICS or IMS TM screen displaying a list of records, a user might enter
S(Select) next to a record to view its details,U(Update) to modify it, orD(Delete) to remove it. - Interactive Utilities: Many mainframe utilities, both IBM-provided and third-party, accept action codes to specify the desired operation (e.g.,
ADD,DEL,MODwhen managing entries in a table or dataset). - Batch Processing Control: While less common, an action code can be passed as a
PARMin JCL to a batch program, directing it to perform a specific function (e.g.,PARM='ACTION=REPORT'). - Data Entry Screens: On a data entry screen, an action code might indicate the disposition of the entered data, such as
SAVE,SUBMIT, orCANCEL.
- Online Transaction Processing (CICS/IMS TM): In a CICS or IMS TM screen displaying a list of records, a user might enter
Related Concepts
Action codes are integral to interactive mainframe applications, especially those developed for CICS (Customer Information Control System) and IMS TM (Information Management System Transaction Manager). They are a primary mechanism for user interaction and command input, directly influencing the flow of transaction processing. Typically, COBOL programs (or PL/I, Assembler) interpret these codes, executing business logic that often interacts with DB2 or IMS DB databases. They work in conjunction with PF keys (Program Function keys) and PA keys (Program Attention keys) to provide a comprehensive user interface.
- Consistency and Intuition: Use consistent and intuitive action codes across related applications or screens (e.g.,
Sfor Select,Ufor Update) to minimize user confusion and training. - Robust Validation: Implement comprehensive validation logic within the application program to ensure that only valid and authorized action codes are accepted for the current user, screen, and data context.
- Clear User Feedback: Provide immediate and meaningful error messages when an invalid or unauthorized action code is entered, guiding the user on correct input.
- Documentation: Clearly document the meaning and usage of all action codes within the application's user manuals, help screens, and technical specifications.
- Security Integration: Ensure that the execution of an action code is tied to appropriate user permissions and roles, leveraging security systems like RACF to prevent unauthorized data manipulation or function execution.