Hi,
Honestly I have never used DB2 before so I could be wrong. Hence i leave it to you whether you take this seriously or not.
To me this seems like a version conflict of GLIBC library. since you are saying it worked fine with RedHat Linux 7.2 it seems DB2 needs the older version of this library.
But installing the old glibc/libc library could break your GNU/Linux installation please be warned.
Shashank