Perdón que comente en español pero creo que suena muy italiano para ser un nombre español... en todo caso sería "Constancia".[trans: Sorry to comment in Spanish but I think it sounds very Italian to be a Spanish name ... in any case it would be "Constancia".]
If you're name is 'Constanza,' you are probably a very confident and special woman; that's my impression whenever I hear this name, and I like it. Just don't shorten to 'Connie." That name conjures up images of an old and bitter spinster who mumbles to herself.