Basically you need increase the heap space for your JVM, to do  so, you can run below code to locate the SAS configuration file:

sasv9.cfg

proc options option=config;
run;

To increase the heap space, CLOSE your SAS session, then make a copy of the file SASv9.cfg before you modify it.
use any text editor which you are most comfortable to open the CFG file, search for "-JREOPTIONS" and locate the parameters


-Xms and -Xmx
for example, if you want to increase the heap to 1GB, change the values for both of these parameters to 1024 as

-Xms1024m -Xmx1024m

then save the file and restart your SAS.

Good luck!