The Time Sharing Option (TSO ) is an interactive command-line interpreter for IBM mainframe operating systems z / OS. Timeshare that allows multiple users to use the computer at a time. You get the CPU allocated, while the other users are on hold with their transactions for a certain time.
TSO for OS/360 was released in 1971 and was originally used on typewriter terminals. With the breakthrough of the screen terminals of the type 3270 it was possible to develop full-screen applications that the command line almost completely repressed ( ISPF, RPF).
The TSO commands can be used in a simple script language CLIST, but which is more and more replaced by the much more flexible REXX.
TSO is the main tool for system administrators and program developers on mainframes running under z / OS.