I need help to increase the java memory and increase the cache

Good evening I installed openfire 3.7 in windows server 2003 using external MYSQL database and authenticating to AD, I need help to increase the memory used by openfire, I have 4gb of ram on the machine, I need to increase the cache of it, already I created the file (openfire-service.vmoptions with the following lines:-Xms512m
-Xmx1024m more memory does not change, creates a maximum of 247.50 MB) which amounts to 96% sometimes used, has already changed the values, more does not change the overall size of the memory of java.
We appreciate all help
openfire-service.vmoptions.zip (188 Bytes)