High Quality Content by WIKIPEDIA articles! In computing, the Time Sharing Option (TSO) is an interactive time-sharing environment for the lineage of IBM mainframe operating systems running from OS/MVT through MVS and OS/390 to the current z/OS. It fills the same purpose as the login sessions used by users on Unix. "Time-sharing" means that many persons can access MVS concurrently but each is unaware that the operating system is being accessed by others - so it appears to each TSO user that he or she is the only user on the system. TSO is most commonly used by mainframe system administrators and programmers because it provides: a text editor; the ability to submit batch jobs, be notified of their completion and view the results without waiting for printed reports; debuggers for some of the programming languages used on System/360 and later IBM mainframes; other vendors' end-user applications, for example for querying IMS and DB2 databases.