[CentOS] Migration to centos 7 and program seg faulting

Everything on Centos 7 seems fine  - except - my program.
I am trying to compile and run on centos 7.

Everything compiles/runs on C6, the executable from C6 runs on C7.
when I compile and run on C7 - I get a SEG fault.
when I debug:
gdb program
break main
run
I get a seg fault at or before main

What might I be looking for in this case?

Thanks,

Jerry