Thanks Hiko_Davis
I was able to Solve this issue.Full details are given below:
After searching for a bit, I stumbled upon this link
db:: 2.77::java.lang.UnsatisfiedLinkError(cause: architecture word width mismatch) 18
One of the posts said that even if you are using a 64 bit version of the Oracle Client (in my case v 11.2.0.4 (x64)), oracle ships only 32 bit OCI driver.
The thin driver still works fine with 64 bit JDK's though.
So basically, libocijdbc11.so is the 32 bit lib present in a 64 bit oracle client installation and hence the error (because 64 bit JVM process tries to load 32 bit OCI driver)
Steps taken to resolve this issue:
1. Downloaded and configured the 32 bit SUN JRE (v 1.8.x) for the Oracle Power Pack agent.
2. In my case had to replace the ojdbc6.jar file present in the package (v 10.3.15) since it has version 11.2.0.3 and is not compatible with the oracle client version that i was using. I replaced it with the corresponding ojdbc6.jar from 11.2.0.4 client installation.
3. Set the LD_LIBRARY_PATH and ORACLE_HOME appropriately so that OCI driver can read the correct TNSNAMES file and pick up the TNSAlias correctly.
4. Restarted the agent service and everything worked like a charm.