RE: mf cobol data file path

I am not sure what you mean by "rm project". Do you mean a managed console application that generates an .exe file? This should work with the app.config.

I can get this to work in a Class Library project called from C# using the following simple example:

      $set ilsmartlinkage
       program-id. testcobdata as "testcobdata.testcobdata".
      $set filetype"21"
           select test-file assign to "Z-SOMPR-FL"
                            organization is indexed
                            access mode is dynamic
                            record key is key1
                            file status is file-status.
       data division.
       file section.
       fd test-file.
       01 test-record.
          05 key1  pic 9(3).
          05 rest  pic x(20).
       working-storage section.
       01 file-status  pic x(2)  value spaces.
       01 ws-field  pic x(30) value spaces.
       linkage section.
       01 myparams  pic x(20).
       procedure division using myparams.
           display "COBDATA" upon environment-name
           accept ws-field from environment-value
           open input test-file
           display file-status
           goback.

C# main program:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace testcsMain
{
    class Program
    {
        static void Main(string[] args)
        {
            Console.WriteLine("In C#");
            Environment.SetEnvironmentVariable("COBDATA", "c:\\testcobdata\\files");
            testcobdata.testcobdata tc = new testcobdata.testcobdata();
            Myparams param = new Myparams();
            param.Myparams = "from C#";
            tc.testcobdata(param);

        }