Don't forget to include 'EXEC SQL'. For IBM mainframe Cobol, how many progrmams DON'T depend on the mainframe environment specific features/services? Probably zero or close to it. I think the environment for other vendors (Microfocus, Accucobol) is a bit more forgiving, I don't have experience with them so can't say for sure.

Another, maybe more subtle mainframe pecularity is how it maps dataset (ie file names) names to 'dsnames' (Cobol source code construct) at runtime, tied together by JCL.