[MLton] Stack size?

[Stephen Weeks]

> My reading is :
>   GC_switchToThread checks ensureMutatorStackInvariant and possibly calls 
>   doGC, which invariably does a minor GC (and may do a major GC) and then 
>   copies the current stack if necessary.
> 
> So, if the stack needs to grow, we definitely perform a minorGC.

It is true that doGC() calls minorGC().  But that may or may not
perform a minor collection.  It depends on whether generational
collection is being used at the time.  I think it's pretty common that
the runtime is not using generational collection, since generational
is only turned on when heap space gets tight.