He 'kept/maintained his cool' [=he didn't get angry or upset] even though it was clear that he was being unfairly treated.
He was struggling to 'maintain his cool/composure'. [=he was struggling not to become angry or upset]
They barely had enough food to 'maintain life'. [=to make it possible for life to exist or continue]
(..) I copied, I approach runway Following you in We're heading -- Ok, you're free Tasty , check your speed. I repeat, maintain control. Avoiding to stall. , check your heading. You're not going to make the runway! I got it. That was a hell of a landing sir! (..)2016 Sully