When DFSMSdss is invoked from an application program, you can use the user interaction module (UIM) to interact with DFSMSdss at points where I/O operations are being performed. UIM exit functions can be used to:

• Replace, insert, delete, or modify a SYSIN record after DFSMSdss has read it or a SYSPRINT record when DFSMSdss is ready to print it.
• Replace, insert, delete, or modify a write-to-operator message before DFSMSdss writes it.
• Insert a statistics record during a logical dump operation.
• Modify the installation options specified in the ADRUFO control block to override the specified options.
• Bypass password and expiration-date checking, or reject the tape volume and request a scratch tape, when DFSMSdss is ready to open a tape.
• Request a specific volume serial when a nonspecific tape is passed to DFSMSdss.
• Get information about the data set being allocated.
• End a task or processing of individual data sets.
• Bypass authority checking for individual data sets. This includes both RACF® and password authorization.
• Bypass serialization checking of individual data sets.
• Show the status of the concurrent copy initialization.
• Specify some information on how a new target data is allocated.