A time-sharing display terminal session manager

The TSO session manager is based on an experimental display facility designed for the IBM Thomas J. Watson Research Center in Yorktown Heights, New York, where a substantial amount of experience has been gained by using the experimental system. Measurements were made by executing a number of typical TSO scripted sessions with and without the session manager. Results have shown that resource consumption in terms of MVS service units necessary to perform a script is slightly less when the session manager is active. In addition, a given script can be performed in an average of thirty percent less elapsed time. The session manager does not cause any additional resource consumption and it avoids calls to the terminal access method because multiple lines of output are written as a single screen write operation. Without the session manager, the TSO address space is swapped on each input request. The session manager allows the user to enter multiple input lines at a time, thus avoiding swaps, and a user can consume more resources per minute because he can be more productive than can a TSO user without the session manager. Typically, a session manager user has a larger paging demand due to the additional code, control blocks, and streams of the session manager. Although the working set is only slightly larger, the total virtual storage requirement is significantly larger, because the session manager streams reside in virtual storage. TSOOUT is typically the largest stream because it has been defined as 200 K bytes in the experimental system.