Hi,
did you follow note 200164 to install the DB2 CLI driver client. The db6_update_client script will install the CLI driver in directory /usr/sap/SAPSID/SYS/global/db6 . dbdb6slib will try to load the DB2 libs from this location as a default.
If you did install the CLI driver in another directory, you need to set environment variable DB2_CLI_DRIVER_INSTALL_PATH to make dbdb6slib aware of this location.
If you did not install a DB2 CLI driver but a DB2 runtime client, you need to create a client instance and set DB2INSTANCE=<instance name> in the environment instead.
Do not try to include the path to libdb2.so in LD_LIBRARY_PATH !
Regards
Frank