Wont let me play

Put the summary of the bug you're having here

*What I expected to happen was.. Minecraft to let me play on server / single player with more ram
Describe what you thought should happen here

*What actually happened was.. crash when i try to enter a world
Describe what happened here

Steps to Reproduce:
1. Put a step by step guide on how to trigger the bug here
2. .. Change ram alloences
3. .. lanuch minecraft / world