We always get out of memory error on Tomcat when the system occupy many memory resource. To avoid this,

we can dedicate how much memory tomcat can use.

1. add JAVA_OPTS=’-Xms1024m -Xmx1024m’ in catalina.sh

2. add set JAVA_OPTS=-Xms128m -Xmx350m in catalina.bat

3. use tomcat service(tomcat.exe) which read JAVA_OPTS from regedit table. add -Xms1024m -Xmx1024m in item  HKEY_LOCAL_MACHINE\SOFTWARE\Apache Software Foundation\Tomcat Service Manager\Tomcat5\Parameters\Java\Options or HKEY_LOCAL_MACHINE\SOFTWARE\Apache Software Foundation\Procrun 2.0\Tomcat5\Parameters\Java\Options

Reference:

http://gcgmh.javaeye.com/blog/291234