IRC, freenode, #hurd, 2011-10-21:

<pinotree> maybe i'm missing something... what's the reason for not
  allowing setting a different stack size in libpthread?

2011-10-23:

<youpi> pinotree: the threadvars implementations
<youpi> which needs to find the variables according to sp value
<youpi> of course, since we now have TLS, threadvards can go away
<youpi> it's simply on the so-long TODO list

tls-threadvar.