What is the meaning of "luban" in the saying of Ali, may God be pleased with him: "You should use luban, for it encourages the heart and removes forgetfulness"?

The narration mentioned about Ali (may Allah be pleased with him) is reported from him in Zad al-Ma'ad by Ibn al-Qayyim, and it states that frankincense (kandar) increases and sharpens the mind, and it has other benefits.