Mainframe Application Regression Testing
Validate that all your application changes have been applied correctly. What needs to be modified has indeed been modified without impacting other areas of the application that should remain untouched.
System Software Upgrade
Ensure that software upgrades to DB2, CICS and similar do not impact application functionality.
Disaster Recovery Site
Periodically check that applications running on disaster recovery site perform with functionality identical to applications running on your prime computer site.