ACUCOBOL-GT comes with a database of terminal descriptions. On UNIX machines, this is called "a_termcap". This database contains encoded descriptions of many types of terminals. You need to select the terminal type in the database that most closely matches the terminal you are using. If you need to, you can add your own entries in the database.
By default, the terminal database should reside in a pre-selected directory on your machine. On UNIX systems (using the Bourne shell), you might use the command:
A_TERMCAP=/usr/local/etc/a_termcap; export A_TERMCAP
The ACUCOBOL-GT User's Guide contains more information about setting up terminals and making full use of their capabilities, and selecting terminal types.