You can control the number of TSO/E logons by limiting them according to groups, such as application developers or end users, and using the logon pre-prompt exit (IKJEFLD or IKJEFLD1) to limit the number of users in each group who can be logged on concurrently. Limiting the logons within groups of users allows you to give certain groups better access to the system than other groups have. For more information about using the logon pre-prompt exit, see Writing a logon pre-prompt exit (IKJEFLD/IKJEFLD1).