d in the same way as the other thread stacks.
If this is not defined and none of the following three macros
is defined, client code must explicitly set
<TT>GC_stackbottom</tt> to an appropriate value before calling
<TT>GC_INIT()</tt> or any other <TT>GC_</tt> routine.
<DT><TT>LINUX_STACKBOTTOM</tt>
<DD>
May be defined instead of <TT>STACKBOTTOM</tt>.
If defined, then the cold end of the stack will be determined
Currently we usually read it from /proc.
<DT><TT>HEURISTIC1</tt>
<DD>
May be defined instead of <