set papersize (size|<x>, <y>)
The papersize option sets the size of output produced by the postscript terminal. This can take the form of either a recognised papersize name – a list of these is given below – or a height, width pair of values, both measured in millimetres. For example:
set papersize a4 set papersize letter set papersize 200,100
A list of recognised papersizes can be found in Figure 3.1.