Hi Ashish,
If the code base you are analyzing is not native COBOL, rather works on top of any specific appliances, it is quite unlikely you find anything interesting from any of these automated scanners. I have often encountered the same issues as well. Most of the scanners with COBOL support doesn't do an impressive backtracking of variable/function references. It can still scans for single flat files in most of the cases and look for potential issues. if your code base has any business process involved that pull records by any supporting web application interfaces, it could be possible to find XSS, SQL issues. At the same time, these validation could also be found on the web application code base itself. Apparently, you can also look into COBOL specific bugs, but often you wouldn't have the complete architecture in the scope of assessment. Most of COBOL developers skip the validation completely and you could encounter truncation, file planting, usage of bad statement, business logic issues etc. Unfortunately all these should be done manually as far as I know.
** security is not very good sound to them **
If you would need to discuss on this, feel free to reach me.
Regards,
Sanoop