I just posted a sample, using gtmci_gtmaccess.zip as a starting point, of GnuCOBOL integration to fis-gtm.
Worked out very well.
If you happen to have a shop with both M and COBOL in use, then this might be a peanut-butter chocolate mixing. Or perhaps a treaty table for arch rivals, depending on point of view. :-)
GnuCOBOL uses intermediate C as part of the compiler tool chain, and the GT.M CallIn features compile and link without a hitch.
Code listings on SourceForge at
https://sourceforge.net/p/open-cobol/discussion/cobol/thread/33e8320b/
That is a seed work, but the potentials make it seem like a worthwhile avenue of exploration.
Thanks to K.S. Bhaskar and FIS for GT.M and the developers with the GnuCOBOL project.
Have good, make well,
Brian