The A_CGI environment variable also ensures that the runtime does not perform user interface functions when running as a CGI program, but it does so by changing the entire server environment. As with any environment variable, A_CGI may affect other COBOL programs in addition to your CGI program.
When A_CGI is set to "1" in the environment, the runtime suppresses warning messages that are normally displayed in a message box. When the runtime shuts down due to an error that is not handled by the COBOL program, it constructs an HTML page containing the shutdown message and sends it to the standard output stream before terminating.