Does file disposition in JCL override the file declared in cobol pgm. E.g I give DISP=MOD in JCL but in program I give OPEN OUTPUT. In this case which one will be taken into account?
DISP=MOD in JCL probably overrides the Cobol OUTPUT option. An Assembler programmer can effectively reset DISP=MOD to DISP=OLD, though I've never done it and I've never heard of it being done. An Assembler programmer also has the EXTEND option in the Assembler OPEN macro to do sort of the equivalent of DISP=MOD. I don't know if there is a similar option in the Cobol OPEN verb.