on stack.
        The ideal setting for this parameter is the actual stack size limit
        enforced by the kernel (as set by <code class="literal">ulimit -s</code> or local
        equivalent), less a safety margin of a megabyte or so.  The safety
        margin is needed because the stack depth is not checked in every
        routine in the server, but only in key potentially-recursive routines.
        If this value is specified without units, it is taken as kilobytes.
        The default setting is tw