In the z/OS environment, a CICS installation comprises one or more "regions" (generally referred to as a "CICS Region"), spread across one or more z/OS system images. Although it processes interactive transactions, each CICS region is usually started as a batch processing|batch address space with standard JCL statements: it's a job that runs indefinitely until shutdown. Alternatively, each CICS region may be started as a started task. Whether a batch job or a started task, CICS regions may run for days, weeks, or even months before shutting down for maintenance (MVS or CICS). Upon restart a parameter determines if the start should be "Cold" (no recovery) or "Warm"/"Emergency" (using a warm shutdown or restarting from the log after a crash). Cold starts of large CICS regions with many resources can take a long time as all the definitions are re-processed.