Couchdb - problem with database

Hi, could you please help me? I create a new user in couchDB this way:

curl -X PUT MY_URL/_users/org.couchdb.user:userName -H "Accept: application/json" \ -H "Content-Type: application/json" \ -d '{"name": "userName", "password": "pass", "roles": [], "type": "user"}'

This method creates two things: document in '_users database' and a database. I have a problem with the database because the name of this one is chosen randomly. The questions: How can I set the name of the database when I create a new user? Or How can I retrieve the name which was created randomly ?