Thread stacks are incrementally grown as their needs expand,
with new memory pages being commited as required. So
thread stacks tend to grow in size to some largest level seen
during their lifetime.

If the largest stack size scenario is rarely seen, then possibly
many of those memory pages will rarely be actually used.

I know thread stack space can be paged in and out as
correlated to thread activity.

Is the thread stack memory also subject to trimming by the
Working Set Manager such that those pages supporting
the rarely used upper stack end are paged out, while the
lower frequently used stack pages are paged in?