eval.c:8091
static void
mark_frame_adj(frame, th)
    struct FRAME *frame;
    rb_thread_t th;
{
    if (frame->flags & FRAME_MALLOC) {
	rb_gc_mark_locations(frame->argv, frame->argv+frame->argc);
    }
    else {
	VALUE *start = ADJ(frame->argv);
	rb_gc_mark_locations(start, start+frame->argc);
    }
    rb_gc_mark((VALUE)frame->node);
}
