The 26-year-old Rosscup has tossed two scoreless appearances with Iowa this season, last pitching on Sunday in Memphis when he struck out three in an inning of work. The southpaw posted no record and a 2.70 ERA (3 ER/10.0 IP) in 10 appearances with the Cubs during spring training before being optioned to Iowa on April 1.
Rosscup went 1-0 with a 9.45 ERA (14 ER/13.1 IP) in 18 appearances covering seven stints with the Cubs last season, striking out 21 batters in 13.1 innings pitched. He spent most of the 2014 campaign with Iowa, where he went 2-0 with four saves and a 2.10 ERA (7 ER/30.0 IP) in 29 relief outings. Rosscup made his major league debut with the Cubs in 2013, posting no record and a 1.35 ERA (1 ER/6.2 IP) in 10 relief outings.
La Stella, 26, is batting .167 (1-for-6) in two games with the Cubs this season. He was acquired from Atlanta in a trade for Arodys Vizcaino on November 16, 2014.