Disable
In the mainframe context, to **disable** means to temporarily or permanently render an entity (such as a resource, function, or user access) inoperable or inaccessible, without necessarily deleting it. This action prevents its use or execution while allowing for its potential re-enabling later.
Key Characteristics
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- Resource State Change: Changes the operational state of a resource (e.g., CICS transaction, DB2 table space, IMS program) from active/enabled to inactive/disabled.
- Operational Control: Often performed by system programmers, operators, or application administrators using specific commands (e.g., CICS
CEMT SET, DB2-STOP, IMS/PSTOP), JCL parameters, or configuration settings. - Temporary or Permanent: Disabling can be a temporary measure for maintenance or problem isolation, or a more permanent state until explicitly re-enabled.
- Scope of Impact: The impact can range from a single instance of a resource to an entire subsystem function, affecting availability and processing.
- Error Prevention: Can be used to prevent the use of faulty or problematic components, or to restrict access during sensitive operations.
Use Cases
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- CICS Transaction Management: Disabling a
CICS transaction(CEMT SET TRAN(xxxx) DIS) to prevent users from initiating it, perhaps during an application upgrade or if the transaction is causing issues. - DB2 Object Availability: Disabling a
DB2 table space(-STOP DATABASE(dbname) SPACENAME(tsname)) to allow for maintenance, recovery, or to prevent applications from accessing data within it. - IMS Program Control: Disabling an
IMS program(/PSTOP PGM program_name) to prevent it from being scheduled, typically during maintenance or error conditions. - RACF User Access: Disabling a
RACF user ID(ALTUSER userid REVOKE) to immediately prevent a user from logging into z/OS or accessing protected resources, often for security reasons or when an employee leaves. - System Functionality: Disabling specific features or functions within a utility or subsystem through configuration parameters to tailor its behavior or mitigate risks.
- CICS Transaction Management: Disabling a
Related Concepts
Disabling is the inverse operation of enabling, which restores a resource or function to an active state. It is closely related to stopping or deactivating resources, though "disable" often implies a more persistent state change or a restriction on *use* rather than just *execution*. It plays a crucial role in system security (e.g., disabling user IDs or access rules), resource management (e.g., controlling availability of CICS transactions, DB2 objects, IMS programs), and problem management (e.g., isolating faulty components).
- Document Changes: Always document *what* was disabled, *why*, *when*, and *by whom*, including the expected duration and re-enablement plan.
- Understand Dependencies: Before disabling a resource, identify and understand all dependent resources or applications that might be affected to avoid unintended outages.
- Communicate Impact: Inform relevant stakeholders (users, application teams, operations) about the impending disablement and its potential impact on services.
- Verify State: After issuing a disable command, always verify the resource's state to ensure the action was successful (e.g., using
CEMT INQUIRE,DISPLAY DATABASE,D PGM). - Plan for Re-enablement: Have a clear procedure and timeline for re-enabling the resource, including any necessary testing or verification steps.