what are the memory caps for threads running as a CLR stored procedure executed by sql server 2005?

what are the memory caps for threads running as a CLR stored procedure
executed by sql server 2005? is it limited by OS only or also by sql servers
memory limits? e.g. lets say my clr stored procedure is executed by sql
server 2005 then it creates 10 threads and each thread builds a giant array
on the stack, is the limits of each array limited by sql server or the os?
do these clr stored procedures run inside the sql server address space or
does sql server fork a sepperat process for each one?