TSO/VTAM

TSO/VTAM provides the capability of using TSO through VTAM®. TSO is a standard feature in MVS™ that provides conversational time sharing.

TSO/VTAM supports the following terminals:

IBM® 3270 Information Display System
IBM 3290 Information Display System
IBM 3767 Communication Terminal
IBM 3770 Data Communication System
IBM 5550 (as 3270) single-byte character set (SBCS) and double-byte character set (DBCS) modes
IBM 8775 Display Terminal
IBM Displaywriter

TSO/VTAM can also support the following non-SNA terminals in conjunction with the IBM Network Terminal Option licensed program:

CPT-TWX Terminal
IBM 2741 Communication Terminal
World Trade Telegraph (WTTY)

The basic elements of TSO/VTAM are the terminal control address space (TCAS) and the VTAM terminal I/O coordinator (VTIOC). TCAS accepts logons from TSO/VTAM users and creates an address space for each user. VTIOC is the interface between TSO and VTAM; it coordinates data flow. TCAS and VTIOC, together with existing TSO components such as the LOGON scheduler, the application programs, the terminal monitor program, and the TSO service routines, make up a TSO/VTAM time-sharing system.

The user logon to the TCAS address space is passed to the TSO user address space without initially establishing a session between the TCAS address space and the TSO terminal. Instead, the session is established between the TSO terminal and the TSO user address space, avoiding session establishment and termination with the TCAS address space and avoiding your receiving message USSMSG7.

TSO/VTAM and TSO through VTAM can reside in the same host processor.

Note: z/OS® limits the number of concurrent TSO/E sessions to eight.