You can implement a CICS EJB server in a single CICS region. However, in a sysplex it's likely that you'll want to create a server consisting of multiple regions. Using multiple regions makes failure of a single region less critical and enables you to use workload balancing. A CICS logical EJB server consists of one or more CICS regions configured to behave like a single EJB server.
Typically, a CICS logical EJB server consists of: