Yeh, while my 7850K manages to play League of Legends maxed out (70-120 frames) and Warframe on all high (40-60 Frames) I wouldn't really bother trying that for demanding things like Last Light or DayZ.
Battlefield is borderline playable on medium settings with this thing...which is impressive...but Battlefield was OPTIMIZED for AMD...DayZ is not...Hell..DayZ isn't even optimized for anything at all...it performs badly...and thus on a GPU as weak as the iGPU of an APU....it's no surprise that it won't run.
If you want DayZ to be playable with your current APU...get a dedicated R7 250 for dual graphics mode or a real graphics card in your PC. (Im going to jam a 750 Ti in mine soonish, yay)