ZACKS Intersection happens to be both an Initial Approach Fix (IAF) as well as the Final Approach fix (FAF). We know this by using the Plan View and this view together. It is further defined as being 20.7 nautical miles from GVO.
The X underneath this area (follow the dotted line) represents the FAF, and the dotted line shows us that ZACKS is a fix and connects all points crossing the dotted line.
Notice the 099° Procedure Track angling right/down from ZACKS. It angles DOWN which indicates a descent, however, because the track descends to an area that has a 3000 nearby, this tells us we must remain AT or ABOVE 3000 Ft. MSL. So, if we are at an altitude higher than 3000 ft at ZACKS, flying the 099° track, we are allowed to descend to an altitude that is AT or ABOVE 3000 ft.
ZACKS INT would only be used as the IAF if directed by Approach, OR flying in from the WEST, if we flew in from the EAST, we would simple enter this approach AT or ABOVE 3000 ft. 279° course inbound and use ZACKS as the Initial Approach Fix.