extern static short SQLAllocHandle(ushort HandleType, int InputHandle, out IntPtr OutputHandle);

Private Declare Auto Function SQLAllocHandle Lib "odbc32.dll" (ByVal HandleType As Short, ByVal InputHandle As IntPtr, ByRef OutputHandle As IntPtr) As Short

    private static extern short SQLAllocHandle(short hType, IntPtr inputHandle, out IntPtr outputHandle);

        if (SQL_SUCCESS == SQLAllocHandle(SQL_HANDLE_ENV, henv, out henv))

            if (SQL_SUCCESS == SQLAllocHandle(SQL_HANDLE_DBC, henv, out hconn))

            SQLAllocHandle(SQL_HANDLE_ENV, SQL_NULL_HANDLE, out environmentHandle);

            SQLAllocHandle(SQL_HANDLE_DBC, environmentHandle.ToInt32(), out dbcHandle);

            SQLAllocHandle(SQL_HANDLE_STMT, dbcHandle.ToInt32(), out stmtHandle);

You must provide an Environment Handle provided by SQLAllocHandle as the first parameter. SQLAllocHandle is a replacement for SQLAllocEnv. When using SQLAllocHandle, you must call SQLSetEnvAttr and set the SQL_ATTR_ODBC_VERSION attribute to SQL_OV_ODBC3 before calling SQLDataSources. You must release Environment handle with SQLFreeHandle at the end.

    rc = SQLAllocHandle(SQL_HANDLE_ENV, 0, out sql_env_handle);

Frees a handle allocated by SQLAllocHandle.