Can you prevent code stripping on specific scripts via link.xml?

I need to make a game smaller and code stripping seems like the big saver. How ever when ever I try to using any of the stripping levels the game crashes on device. I don't fully understand the stripping process but i was thinking that it was possible that some our network code needed to be left out the stripping process. When I was searching around it looked like the link.xml was made specifically so you can specify sections of the project that need to be left out the stripping process. If so how would i specify these parts. I already looked at the little section on the link.xml and it was less then helpful on understanding how to add things.