Critical error

Hello,

I'm building a quite big level, but when i want to compile it, it get the following error:

----- Critical error -----
Block outside level boundaries!
Use -bound XXX to increase size!
Press any key...

I've read something about the x,y, and z dimensions have to be lower than a specific number, but I want to keep the level big; i don't want to make several loadingpoints. I have the following questions:
- What can i do to avoid this error?
- what is '-bound XXX' and how can i use it?

I got this error last night too.