going to reply to your 4 comments.
1 - you do not need to migrate to Microfocus - I was just stating what we did on our project.
regarding the using client calls this goes to application design.
. application layer
. data layer
the above apply to any language being it Cobol or C#
In our case we had
. cobol application -> core IO Module (Cobol) -> IMS DB calls
and we converted to
. cobol application -> core IO Module (C#) -> Sql statements using SQL Client
2 - Show this to your cobol developers - they will most likely understand it and explain to you what I mean
3 - Any cobol developer will know what to do and the one that supplied the file has probably done it already, but depending on volumes of data it may be better to do it differently - but this is outside the help I can give here.
4 - to that I ask "Why not?"
possible reasons why
. keep extensive business logic intact
. avoid making same mistakes on code that have already been fixed on cobol
. reuse cobol developers that know the application without the need for a full retraining in another language
Obviously all this is going to be highly dependent on what the application does, how extensive it is in terms of both business logic and volumes of data and how it is processed.
But for me as an Architect it would require that all possibilities are put on the table and then pros and cons analyzed and all alternatives are given so a decision can be taken on the way to go.
And my question here was not to suggest in any way that the decision is wrong - was only to confirm that the client has indeed taken this option in consideration - seen many that were not even aware they could do it.