IBM Mainframe Application Programming Resources:
http://www.ibmmainframes.com/downloads.html

IBM Mainframe Language References:
http://www.ibmmainframes.com/mybook.html

IBM Mainframe Information Zone:
http://www.ibmmainframes.com/info.html

Common Compile and Run Procs:
http://www.ibmmainframes.com/jcls.html

COBOL: A Best Practice:
http://cobolreport.com/pp/

Open Source COBOL:
http://cobolreport.com/os/