Expiration Check

Enhanced Definition

An expiration check in the mainframe context is the process of verifying whether a resource, data element, or security credential is still valid for use based on a predefined expiration date or retention period. It is a critical mechanism for data lifecycle management, security, and resource optimization within z/OS.

Key Characteristics

- Date/Time Driven: Relies on a comparison between the current date/time and a stored expiration date (EXPDT) or a calculated date based on a retention period (RETPD).
- Automated or Programmatic: Can be performed automatically by system components like DFSMS or RACF, or explicitly coded within application programs (e.g., COBOL, PL/I).
- Resource Agnostic: Applicable to various mainframe resources including data sets, tape volumes, security certificates, user IDs, passwords, temporary files, and application-specific data records.
- Action Triggering: Upon detection of an expired item, specific actions are triggered, such as scratching/deleting data sets, disabling user accounts, revoking access, or flagging records for archival.
- System Integration: Often integrated with Job Entry Subsystem (JES) for SYSOUT management, Storage Management Subsystem (SMS) for data set lifecycle, and External Security Managers (ESM) like RACF for security credentials.

Use Cases

- Data Set Retention: DFSMS uses EXPDT or RETPD specified in JCL (DD statement) or SMS policies to automatically scratch (delete) data sets that have passed their expiration date.
- Tape Volume Management: Ensuring tape volumes are not prematurely overwritten by checking their EXPDT to determine if they are still protected or can be reused as scratch tapes.
- Security Credential Validity: RACF (or ACF2, Top Secret) performs expiration checks on user IDs, passwords, and digital certificates to enforce security policies and prompt for updates or disablement.
- Application Data Lifecycle: COBOL or PL/I applications might perform expiration checks on records (e.g., customer subscriptions, policy validity dates) to determine if they are active or should be archived/purged.
- Job Output Cleanup: JES manages the retention of SYSOUT data sets based on JCL parameters (HOLD=YES, OUTLIM, RETPD) or system defaults, performing expiration checks to purge old output.

Related Concepts

Expiration checks are fundamental to Data Lifecycle Management (DLM) and Information Lifecycle Management (ILM), ensuring data is available when needed and properly disposed of afterwards. They are tightly coupled with Storage Management (especially DFSMS) for automated data set and tape volume handling, and Security Management (RACF) for maintaining the integrity of user access and authentication. The parameters for expiration are often defined in JCL or system configuration, making it an integral part of job processing and system administration.

Best Practices:

Define Clear Retention Policies: Establish and document explicit data retention and expiration policies for all data types, aligning with business, legal, and regulatory requirements.
Automate Where Possible: Leverage DFSMS and ESM capabilities for automated expiration checks and actions to minimize manual intervention and reduce errors.
Regular Audits: Periodically audit expiration settings and expired resources to ensure compliance, identify potential issues, and verify proper cleanup or archival.
Implement Warning Mechanisms: For critical resources like security certificates or user IDs, implement alerts or warnings well in advance of their expiration to allow time for renewal or action.
Backup/Archive Strategy: Ensure that critical data slated for deletion due to expiration is properly backed up or archived according to disaster recovery and compliance strategies before being scratched.