Jackson was recalled from Triple-A Indianapolis on Friday.
Acquired from the Dodgers at the end of June, Jackson will now get his first opportunity with the Pirates, replacing Dauri Moreta (back) in the Pittsburgh bullpen. Jackson has pitched to a 3.38 ERA and 1.18 WHIP in five appearances with Indianapolis to date -- a significant improvement on the 5.86 and 1.54 marks he had with Oklahoma City prior to the trade.