Increasing the JVM heap for RSA, RAD, and other Rational or Eclipse products

I ran into an issue this past week where several times my Eclipse workspace ran into out of memory errors. I’m running Rational Software Architect (RSA), with several additional plugins, plus run one instance of WAS, and another instance of WebSphere Portal. Yes, I know. Yikes! That said, I have the horsepower for all these systems with a decent powered laptop (a quad-core lenovo Thinkpad w520 with 16GB of RAM).

So I’ve never touched the top end of the memory on this laptop even running all this at the same time (along with multple browsers, Lotus Notes, putty, Word, and at least 2-3 other apps). So my problem was not my hardware. Rather its my JVM for RSA. I installed the 32 bit version of RSA as one of the plugins I’m using (HATS toolkit) requires the 32 bit version. You can increase the maximum heap size in the eclipse.ini settings found under x:IBMSDPeclipse.ini , assuming you installed your environment off the root drive. In this file the values that come after the vmargs statement are passed directly to the JVM. Xmx is setting for the maximum heap size. I recommend that you change both this size and the Xms setting (the starting heap size). The Xmx/Xms setting should default to to 1024/100 respectively. I’ve increased it to 1536/256. Be very careful how you set these. Make a quick back up copy before you make your changes.


You also MUST update the line

-vm ‘install directory’jdkjrebinj9vmjvm.dll
-vm ‘install directory’jdkjrebinjavaw.exe

Otherwise, it will not respect the variables and WILL crash your Eclipse instance. 

There is a great blog post on these various settings that I found at
You may need to tweak some other settings as you go to manage performance. Don’t forget that in version 8 of the products you can dynamically reduce your memory foot print:

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One Response to “Increasing the JVM heap for RSA, RAD, and other Rational or Eclipse products

  • Thanks for all of the tips. I had struggled to increase the memory available to my RSA instance. Looking forward to better performance w/ these tips.