Whats the name of that animated movie about the kid and the giant?

There is this animated movie that i vaguely remember seeing as a
little kid. It probably came out around the 80's or 90's or something.
Its about this kid with glasses who wakes up in the middle of the
night and all of the sudden he gets carried away by a giant in a black
robe. When the giant takes off his robe, it turns out that he is a
good giant. I don't really remember anything else about it. What is it
called? Does anyone even know what i am talking about?