.Tm -  top margin

Number of blank lines to be placed at the top margin of the page.  These lines add lines to the page height above and beyond the number of lines specified in the .ps command.  Default value is 0.  This is set using the syntax

Localfileidentifier.tm=number;

or in the example putex5.gms

my1.tm=3;

This works for any of the page control (pc) settings.