Out of memory issues can have many different root causes. Bart has valid points with the questions he asked. There are some more questions to ask:
- Which operating system are you using?
- What is your Java heap space set to?
- What happens if you run of the example models from SimBiology?
- Which release of SimBiology are you using?
It might be worth contacting Technical Support if you assume the issue is due to your model and don't want public to see your model.