Overview

TSO/3270 passthrough mode allows full-screen 3270 interactive applications to be invoked from and run in a shell environment. A full-screen 3270 interactive application can exercise significant control over the 3270 terminal device by sending and receiving 3270 data, and can thus take full advantage of the display and input/output capabilities of 3270 devices, as opposed to a line-mode only application.

TSO/3270 passthrough mode allows a POSIX application program that is invoked from a shell command prompt to change its mode of terminal interaction from line mode to TSO/3270 passthrough mode. In line-mode interaction between the terminal (in this case a 3270 device) and an application program, the application can read and write lines of text data delimited by newline characters. While in TSO/3270 passthrough mode the application can read and write 3270 data, allowing it the same degree of control over the 3270 device as an application that uses the TSO TPUT and TGET APIs.

Note: z/OS UNIX does no validation of the data stream prepared by the application; therefore, sending data that is inappropriate for the device (for example, that exceeds the device's capabilities) may cause unpredictable results.
TSO/3270 passthrough mode is an extension to that subset of the POSIX General Terminal Interface (GTI) supported by z/OS UNIX for 3270 devices. The interface provides the following functions:
  • The application program can detect whether a file descriptor represents a 3270 terminal that can be put into TSO/3270 passthrough mode.
  • The application program can change from line mode to TSO/3270 passthrough mode and back again.
  • An application can determine the current mode (line mode or TSO/3270 transparent mode).
  • An application can indirectly issue certain TSO APIs (such as TPUT, TGET, and TPG) to send or receive 3270 data to the terminal.
  • An application can indirectly issue the IKJEFTSR API to invoke most TSO commands.
  • A program can return from 3270 transparent to line mode at appropriate times, such as upon normal or abnormal termination of a child process that had been operating in TSO/3270 passthrough mode.

TSO/3270 passthrough mode provides basic functions to read and write 3270 data from a program that is invoked exclusively in the shell environment provided by the combination of the z/OS UNIX shells and utilities, the OMVS command processor, and related kernel pseudoterminal and line discipline functions. The programming interfaces (using commands that are imbedded in the data read and written) are direct mappings of TSO TGET and TPUT.