The gateway runs within z/OS® UNIX and is invoked upon a request for a TSO or ISPF command from the client application. To run a requested command, the gateway establishes a TSO address space and, if the request is for an ISPF command, data sets are allocated and an ISPF session is also initialized. After completion of the command, the results are returned to the client.

If requested by the client, the gateway maintains the state of the TSO/ISPF session for any subsequent client function requests for the user. Otherwise, the interface terminates the TSO/ISPF session. The advantages of maintaining a user's TSO/ISPF session on z/OS are in bypassing the overhead of having to establish a new session for every TSO or ISPF command request and in adding an inherent ability to maintain state data between calls from the client.

The gateway does not provide the data transport between the client and z/OS host. The gateway is designed to interface with an authenticated connection between the client and z/OS host such as the HTTP protocol (web-based services), direct TCP/IP socket connections, or any other means through which data and commands can be exchanged between the client and z/OS host.