Per-segment overflow ranges. One method includes acts for handling overflows of a mark stack. A reference to an object is accessed. The object is processed by attempting to place references to other objects referenced in the object onto a mark stack. An overflow condition of the mark stack is detected. A range in a segment is defined which includes the object that caused the overflow condition. The range is assigned on a per segment basis such that the range is defined to only include addresses in a single segment.