My Husband Has Had Green Solid But Soft Poop Twice

My husband has had green solid but soft poop twice now...it's a very dark green. 1st bm was on Saturday that had both green and brown poop. The second bm was tonight and it was all green. He doesn't eat vegetables at all. No other symptoms of pain, or discomfort and it's not runny or frequent. He is 61 years old and takes 5mg lisinopril daily a .05 xanax (3x daily) and 20 mg Enalapril daily. thank you