After using libdb2o.so ( instead of libdb2.so ), Program throws an DB2 / LUW SQL Error out of range ( -302 ) by the same size/length of std::string

Question

I have a strange question about the using of libdb2.so and libdb2o.so. My C++ Program have an string with length/size 33. I'm trying to write that string inside a database column of character which have a size of 35 character. Important: That string have a german umlauts (ü) and several special characters. It looks like that:

Xüxxxxx / Xxxxxxxxxxxx-Xxxxxxxxxxx

If my program ran with the hard-linked libdb2.so it ran perfectly and I have no SQL Error for many month. After a view month I thought would be a great idea to use the libdb2o.so which I did not hard-linked inside my C++ Program. All other SQL Statements went well, but my INSERT-SQLs got an error like that:

[IBM][CLI Driver][DB2/AIX64] SQL0302N The value of a host variable in the EXECUTE or OPEN statement is out of range for its corresponding use. SQLSTATE=22001

After some analysis I regonized that I could have an encoding problem, but not inside my std::string. The size of std::string did not changed. It is still 33 long. If I replaced my umlauts to normal character (ü => u) it worked fine, but it is not what I want.

I thought if I using libdb2o.so I have the standard encoding UTF8, but it looks like it could not be, or? If I tried to set the UTF8 inside my connection string like that above, it did not worked and I got an error of "unkown paramter inside connection string"

CONNECTION_STRING=DRIVER=libdb2o.so;Database=XXXX;Protocol=tcpip;Hostname=XXXX;Servicename=XXXX;UID=XXXX;PWD=XXXX;

Well, I did not found a simpel solution (okay I found NO solutions or explanations), therefore I would be greatful if someone know how I could fix that problem. Maybe any ideas to simpel use UTF8 inside my INSERT without changing the content of my std::string?

Am I on the wrong track that the problem could be UTF8 encoding? Any other ideas?