Importing resource and descriptor definitions from an RDDS by using the IMPORT command

After IMS is up and running, use the IMPORT DEFN command to import resource and descriptor definitions from a resource definition data set (RDDS).

  • If the definition is for a resource or descriptor that is unknown to IMS, IMS creates the internal control blocks needed to manage the resource or descriptor.
  • If the definition is for a resource or descriptor that exists in IMS and OPTION(UPDATE) is not specified, the definition is not imported.
  • If the definition is for a resource or descriptor that exists in IMS and OPTION(UPDATE) is specified, the definition is imported and the existing runtime resource or descriptor definition is updated with the attributes from the imported definition.

Resource and descriptor definitions can be imported from either the system RDDS with the most current resource and descriptor definitions, or an RDDS that is specified using the RDDSDSN() keyword on the IMPORT DEFN SOURCE(RDDS) command. The RDDS that is specified with the RDDSDSN() command keyword can be a system RDDS or a non-system RDDS. A system RDDS is one of the RDDS data sets that is defined with the RDDSDSN() parameter in the DYNAMIC_RESOURCES section of the DFSDFxxx member of the IMS PROCLIB data set. A system RDDS contains all the resource and descriptor definitions for a single IMS system. If you are using the automatic import or automatic export function, each IMS system must have its own set of system RDDS data sets.

If an RDDS contains multiple definitions for the same resource or descriptor, the last definition imported is the definition that is used to create or update the runtime resource or descriptor definition.

Resources defined by IMS such as the Fast Path utility (DBF#FPU0) and the IMS defined descriptors (DBFDSRT1, DFSDSDB1, DFSDSPG1, and DFSDSTR1) are restricted and therefore not allowed to be specified on the IMPORT DEFN command.