Problem:
You may have a character based screen application that you want to run inder Windows as a full screen display. However, when you run it the screen display may be much smaller than required and you may want to extend the screen to be a full screen making the screen a 25 lines by 80 column screen.
Resolution:
COBOL doesn't set a 25x80 screen as default for console based applications. Instead, the screen characteristics are set by Windows.
When you originally developed your app, 25x80 was probably the standard screen size, although there were some exceptions where 43 and 50 line screens were used. (These subsequently led to the intorduction of the C4 and C5 runtime switches).
The only way to get a full screen is by clicking the top left corner of the application screen and selecting 'Properties'. One of the options then available is 'Full Screen'.
However this only expands the display to cover the full screen and does not necessarily set up the screen to be a 25x80 screen.
To limit your screen size to 25 lines you need to take this a little further. Once you've selected 'Full Screen' you then need to select the 'Layout' tab. On there you'll see the 'Screen Buffer Size' and 'Window Size'. If you set the 'width' to 80 and 'height' to 25 on both you should get a 25x80 screen.
Adjust these and you will see how Windows controls the screen.
The C4 and C5 switches are for specific screens for very old applications where a non-standard screen was used. There is no "C" switch to set it to 25.
However, there is a run time tuneable that does allow you to set the number of lines that COBOL will work in. This is the 'screen-lines' runtime tuneable. Setting this would restrict the COBOL program to working within the number of lines specified. However it does not adjust or control the screen itself in any way or create a 'full' screen. It just forces the application to work with the number of lines specified.
If you want to test this look up screen-lines in the On-line Help and it give a description of the runtime tuneable. If you follow the links you should be able to find where it explains how to set and use run time tuneables.
