DFSMSrmm returns return codes and reason codes to your application program in the general purpose registers and also as data in your output buffer as follows:

• Return codes and reason codes issued as a result of processing of your subcommand request. Refer to z/OS DFSMSrmm Managing and Using Removable Media for information about these codes.
• Return codes and reason codes associated with the API itself. These are the return codes and reason codes listed in EDGXCI return and reason codes for macro EDGXCI.
• Return and reason codes from system services. DFSMSrmm uses various system services, such as catalog services, to process the subcommands from your application program. When DFSMSrmm receives a non-zero return code from a system service, the DFSMSrmm API places the return code and associated reason code in your output buffer as structured fields, along with a name to identify the service. See System return and reason code structured field introducers for more information.