When you do not run the DFSMSrmm subsystem under the JES2 or JES3 subsystem, there are functions in DFSMSrmm that cannot be used because they require job entry subsystem services for successful processing. JES2 or JES3 is required if you want to use the NOTIFY function. The NOTIFY function allows you to use DFSMSrmm to notify volume and product owners when the volumes they own become eligible for release or when product volumes are added. Other functions, like displaying diagnostic messages from SORT during inventory management, also require JES2 or JES3 for successful processing.