A Stack that is managed separately from the threadlocal one.
Typically, using the threadlocal APIs
is encouraged because they enable sharing across libraries, where each
re-use lowers the amortized cost of maintaining allocations. But, if
full control is necessary this API may be used.
Buffers an iterator to a slice on the threadlocal stack and gives temporary access to that slice.
Panics when running out of memory if the iterator is unbounded.