Gymnastics Arch Body Position: Suck in Abs and Squeeze the Glutes?

Question

In gymnastics, I am working on the Arch Position for the back handspring. In the Arch body position, should I follow some of the same principles of the hollow body position?

(a) Should I suck in the abs/stomach? (b) Should I squeeze the glutes also?

I got the back handspring, just working on the finer principles.