This topic is covered in the NAT932 documentation at Natural 3GL CALLNAT Interface - Usage, Examples
As noted in the documentation, the CICS transaction must start Natural, which runs a program (that you supply) which invokes your COBOL “driver program”. NCIXCALL is called with a LINK after NCIXCPRM is called to set up the parameter list. The Natural object to be called is a specific module type “subprogram” (invoked by other Natural programs with CALLNAT) - not “subroutine” nor “program”.
Thanks. I saw the example and if it is must for a CICS transaction to start Natural which runs a Simple Natural program like CALLCOB then CALLCOB will be driver(or first program initiated bythe transaction) and not my COBOL program.. I saw this pattern and I thought is it possible to have COBPGM directly as the first program(driver) mapped to transaction and then do the NCIXCALL & NCIXCPRM. I assume that design pattern is not allowed. It should always be to start Natural, invoke a CALLCOB kind of Natural program and then go out to my COBOL program and come back in with the required subprogram call.