The first thing to take in account is the computer RAM memory limit so you shouldn't assign a memory higher than or equal to this one.

Moreover, it must be taken in account that other applications and even the Operative System need memory too.

For instance, if the computer have 1GB RAM memory and Windows need 500MB to run, you should assign at most 500 MB to gvSIG. If the computer had 2GB RAM memory, it would be possible to assign even 1024MB. In no event shall assign more than 1512MB.

If we are working in Windows,  the memory should be set in gvSIG.ini file
(/Program files/gvSIG_version/bin/, and from gvSIG 1.12 in /Program files/gvSIG_version/). But if we are wonking in Linux, it should be
set in gvSIG.sh file (/home/user/gvSIG_version/bin/, and from gvSIG 1.12 in /home/user/gvSIG_version/).

For this, in this file the expression Xmx500M should be replaced by the same
expression but with the new memory amount.
For instance, if the memory to assign is 1024 M, the expression must be Xmx1024M.