DFSPLPP0

DFSPLPP0 is the IMS Module Preload Proclib Processor. It builds a list of modules to be preloaded into a region. It does not actually load the modules.

The modules to put in the preload list come from several sources. Modules DFSIIN10 and DFSIIN30 contain lists of modules to preload. The lists contain flags that indicate which environments require the preloaded modules, for example, MVS versus VS1 or online versus batch.

The user can specify a list of modules to be preloaded or managed by virtual fetch. This list is in the IMS PROCLIB with a member name of DFSMPLxx, where xx is specified in the MVS PARM for the region. This list is loaded and the modules are processed. For each module to be preloaded, an MVS BLDL SVC is issued to obtain the module attributes.

Finally, IMS code can contain other lists of modules to preload.

Hints

DFSPLPP0 is invoked only once during region initialization, so it should not have a large impact on the job as a whole. If there are many modules in the DFSMPLxx user preload list, and there are many libraries, or many members in a few libraries in the region STEPLIB, the BLDL issued for each module in the preload list, SVC 018, can show a measurable amount of CPU.

Reference Sources

More information is available in the IMS SVSOURCE Library Data Set. See your IMS systems programmer.