If you are using CICS/XRF in a multi-MVS environment with DB2®, you should use global resource serialization to ensure the integrity of DB2. In the case of an alternate CICS® system taking over from an active CICS system, the original DB2 region that the failed CICS was using must be completely terminated before a new DB2 can be restarted with the newly active CICS. Global resource serialization can reduce the risk of data integrity problems caused by concurrent execution of DB2 on both MVS™ systems. One recommendation is to set up global resource serialization to control key DB2 data sets so that only one DB2 region is allowed to update them at the same time.