Maximum number of threads

> In a single-threaded process, the address space reserved for the stack can be large and difficult to overflow. Multi-threaded processes contain multiple stacks, though; those stacks are smaller and are likely to be placed between other virtual-memory areas of interest. An accidental overflow could corrupt the area located below a stack; a deliberate overflow, if it can be arranged, could be used to compromise the system.

So, if I understood things right, the change was about growing the guard size of all of the program's threads.