Enabling and disabling IMS functions

If an IMS function is not enabled by default, you can enable the function dynamically while IMS is running by issuing the UPDATE IMSFUNC command. Or, you can enable the function statically by defining the function as enabled in the DFSDFxxx member of the IMS PROCLIB data set, and then cold starting IMS.

To enable IMS functions dynamically, ensure that OM and SCI are enabled.

Changes that you make by using the UPDATE IMSFUNC command are logged in the x'22' map byte x'31' log record and are recoverable across an IMS restart. For example, if a function is enabled in the DFSDFxxx member and later disabled by using the UPDATE IMSFUNC, the disabled value is recovered if IMS restarts.

If you change a function enablement value by using the UPDATE IMSFUNC command and IMS is cold started, one of the following situations occurs:

For local functions, the enablement value is retrieved from the DFSDFxxx PROCLIB member during cold start. In this case, the UPDATE IMSFUNC command might need to be issued following the cold start to return the enablement value to a previous state.
For global functions, if you use RM, CQS, and a resource structure, the enablement value is retrieved from the resource structure during cold start.
For catalog functions, the enablement value is retrieved from the catalog during cold start.

After installing a PTF that includes an IMS function that is not enabled by default, use one or more of the following steps to enable or disable the function:

To enable IMS functions statically, define the enabling parameter for the function in the DFSDFxxx member, and then cold start IMS.
To enable IMS functions dynamically, perform the following steps.
1. Restart IMS.
  When IMS restarts, message DFS4878I is issued to display the current IMS function level.
2. Issue the UPDATE IMSFUNC command with the SET(ENABLED(Y)) option specified.
  
  For IMS catalog functions, the enablement value is stored in the IMS catalog after you issue the UPDATE IMSFUNC command.
  
  For all other global IMS functions, if you use RM, CQS, and a resource structure, the enablement value is stored in the resource structure.
3. Optional: For local functions, define the function as enabled in the DFSDFxxx member so that the function remains enabled at the next IMS cold start. For global functions, if you do not use RM, CQS, and a resource structure, define the function as enabled in the DFSDFxxx member so that the function remains enabled at the next IMS cold start.
To disable the function statically, define the function as disabled in the DFSDFxxx member so that the function remains disabled at the next IMS cold start.
To disable the function dynamically, perform the following steps:
1. Issue the UPDATE IMSFUNC command with the SET(ENABLED(N)) option specified.
  
  For IMS catalog functions, the enablement value is stored in the IMS catalog after you issue the UPDATE IMSFUNC command.
  
  For all other global IMS functions, if you use RM, CQS, and a resource structure, the enablement value is stored in the resource structure.
2. Optional: For local functions, define the function as disabled in the DFSDFxxx member so that the function remains disabled at the next IMS cold start. For global functions, if you do not use RM, CQS, and a resource structure, define the function as disabled in the DFSDFxxx member so that the function remains disabled at the next IMS cold start.