Description

   This routine obtains the value of the stack address attribute of
   the thread attributes object specified in the attr argument and
   stores it in the location specified by the stackaddr argument.
   The specified attributes object must already be initialized when
   this routine is called.

   The stack address attribute of a thread attributes object points
   to the origin of the stack for a new thread.

   Unlike pthread_attr_getstackaddr(), this routine is a much more
   reliable portable interface. With the POSIX standard pthread_
   attr_getstackaddr(), a stack is specified using a single,
   undefined, address. An implementation of the standard can only
   assume that the specified value represents the value to which the
   thread's stack pointer should be set when beginning execution.
   However, this requires the application to know how the machine
   uses the stack. For example, a stack may "grow" either up (to
   higher addresses) or down (to lower addresses), and may be
   decreased (or increased) either before or after storing a new
   value.

   The Threads Library provides an alternative interface with
   pthread_attr_getstackaddr_np(). Instead of returning a stack
   address, it returns the base (lowest) address and the size.