You tried to invoke the OMVS command from a terminal that is not a display terminal. When the OMVS command tried to find out the screen size, it determined that the terminal was not a display. The OMVS command must be entered from a 3270-type display terminal, or from a workstation with a 3270 emulator.
The OMVS command ends and returns to TSO/E without starting a shell session.
The terminal in use is not a display terminal. For more information, see return code 8 from the GTTERM macro, in z/OS TSO/E Programming Services.
Make sure that you are logged on to a display terminal before you enter the OMVS command. If you are logged on to a display terminal, contact the system programmer.