What are you talking about? There is the entire mass of a very large star making up a black hole.
I was under the impression that black holes consumed matter and released it as energy. I'm not a physicist.
A black hole is created when a star over a certain mass threshold collapses, due to its fusion reaction ceasing. The gravitational force compacts the matter in to a singularity, making the newly formed black hole's gravitational field extremely strong. Anything that crosses the event horizon, cannot escape, including energy. The energy consumed eventually is radiated back out via Hawking Radiation.