Lebanon was under ottoman empire for 400 years till WW1. At this time no records whatsoever. After WW1 France took over Lebanon and Syria, declared Great Lebanon in the beginning of 1920's. the first census was made later in the 20's and the second in 1936. If your grandfather was not in Lebanon during the census you can not find any document. Any way good luck in your search. The only thing you can gather is information from people from the same village where he was born if there is someone who remembers hearing about him.