Green’s Dictionary of Slang

(US black) a close ally, a backup, a lookout.

1994		N. McCall Makes Me Wanna Holler (1995) 75: I looked for my stickman, Shell Shock.
2000		P. Beatty Tuff 156: Typecast as the heavy, Winston played the same part in the sham as always: he was to be the stick man — a bit player who stayed away from the action, vigilant for the police and the suckered.
2000		Other Side of the Wall: Prisoner’s Dict. July 🌐 Stick: Used by prisoners to designate someone as their pal or homeboy. The term is used by the correctional officers when referring to each other or other staff members as in the person who will stick by them in case trouble breaks out. Also called ‘stick man.’ (VA).