Jackson was called up from Triple-A Oklahoma City and will pitch behind starter Tyler Anderson against the Rockies on Sunday, Fabian Ardaya of The Athletic reports.
Anderson may not have his usual starting workload in his final start of the regular season, and Jackson will follow in an attempt to limit the workload for the rest of the bullpen. The right-hander has delivered 5.2 scoreless frames across his three big-league appearances this year.