The list of parameters for an external stored procedure is very specific. It includes the IN, OUT, and INOUT parameters that are specified when the stored procedure appears in a CALL statement. It also includes the SQLSTATE result code.
A C or C++ external stored procedure can have 0 to 256 input/output parameters. The types that you use as input/output parameters correspond to SQL data types in the procedure invocation. For more information, see SQL Data Type Mapping.
Additional parameters might be required, depending on the parameter passing convention you choose.
Parameters are always specified as pointers to the data.