Minecraft wont start

I try to Play Stoneblock 2 from Twitch. I download the modpack start minecraft and i have this problem: "Error: Could not create the Java Virtual Machine. Error: A fatal exception has occurred. Program will exit." If I turn off Java arguments i have 0.5G RAM in game, the game will start (Error not appear), but 215 mods is too much for 0.5G. What should i do? In oryginal minecraft launcher problem dont appear. Pls help