Kmax runs in the Java virtual machine.  The VM is usualy responsible for assigning the initial memory partition and expanding the partition if Kmax needs more memory.  If you are running Kmax from the command line, or from a batch (.bat) or shell (.sh) file, you can specify the initial memory or maximum memory using the java command -mx, -Xms and -Xmx option switches.  See the documentation for the Java VM for more information.  (Type "java -help" or "java -X" on the command line for an explanation.)