Usually I work from draw length to calculate the length of stave/bow. Double the draw length plus 10-20% for a bow with a narrowed, nonbending handle. Double the drawlength for a bend-thru-the-handle twyle bow.
With that in mind, your stave would handle a 25" draw length if you utilize the whole thing, tip to tip, for working limbs. If you wanna really push things (depending on your experience level), you could flip the tips, back with sinew or rawhide, make it a bit wider than normal, and try for a little overdraw. Good luck.