Jan-Erik's Weblog - Setting JVM options for Tomcat 4 when running as a service: "I needed to specify JVM memory options for Tomcat. The trouble was that Tomcat was running as a Service on Windows and SETENV.bat etc could not be used. As it turned out, the solution was realy simple.
* Start Regedit and navigate to HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Apache Tomcat 4.1\Parameters
* There are a number of JVM Option Number x string values, add more as x+1 etc and enter your values
* In my installation I added a JVM Option Number 4 and set it to -Xms64m
* Restart Tomcat"