Java Database Connectivity (JDBC)

To undersdande my problem, please see the code below:

CODE A:
sql = "INSERT INTO DEC VALUES ('999999999999999.99',999999999999999.99')";
PreparedStatement stmt = con.getConnection().prepareStatement(sql);
stmt.executeUpdate();

CODE B:
sql = "INSERT INTO DEC VALUES (?, ?)";
PreparedStatement stmt = con.getConnection().prepareStatement(sql);
stmt.setString(1, '999999999999999.99');
stmt.setDouble(2, 999999999999999.99);
stmt.executeUpdate();

The Problem:

The table DEC tha I used has two columns, the first is a char(50) and the second is a Decimal(17,2) and its in DB2 running on AIX.

If I execute the firs statement, it execute very well. If I execute the second, the follow exception occurs:

COM.ibm.db2.jdbc.DB2Exception: [IBM][CLI Driver][DB2] SQL0302N The value of a host variable in the EXECUTE or OPEN statement is too large for its corresponding use. SQLSTATE=22003

If I reduce on algarism on number (14 digits and two decimals) the result is:
String Decimal
-------------------------------------
CODE A 99999999999999.99, 99999999999999.99
CODE B 99999999999999.99, 100000000000000.00

My question:
Is the code incompatible? Why?
Does anybody knows what is wrong?

I need help urgent!!!

Thanks in advance

Renato Melo