All Version 1 and Version 2 applications are binary compatible, meaning they will run with a DB2 Universal Database Version 5 product without change. In some cases, the DB2 CLI initialization file (db2cli.ini) may require customization in order for the applications to run. For more information about this file and the various keywords, refer to "Configuring db2cli.ini".
If applications are recompiled, some minor changes may be required, these changes can be minimized by setting the DB2CLI_VER define, refer to "Setting the DB2CLI_VER Define" for more information. The environment attribute SQL_ATTR_ODBC_VERSION can also be used to minimize the changes required. See the attribute description in SQLSetEnvAttr - Set Environment Attribute for more information.