Subject complement is a grammatical function.
The terms predicate nominative and predicate noun are also used for noun phrases that function as subject complements. The term predicate adjective is sometimes used for adjective phrases that function as subject complements. Predicate nominative, predicate noun, and predicate adjective are also grammatical functions.
Brinton, Laurel J. & Donna M. Brinton. 2010. The linguistic structure of Modern English, 2nd edn. Amsterdam: John Benjamins Publishing Company.
Hopper, Paul J. 1999. A short course in grammar. New York: W. W. Norton & Company.
Huddleston, Rodney. 1984. Introduction to the grammar of English. Cambridge: Cambridge University Press.