There are three different types of errors that can be encountered when using the ESL CICS support DLL. The first type of error is discovered by the ESL CICS DLL when CICSInitiate is called. This type of error is usually caused by invalid arguments, or a resource allocation problem (the DLL cannot allocate memory, or create a thread, etc.). When this type of error is encountered, an error message is written to the errorlog, CICSInitiate returns 0 to indicate that an error has occurred, and a stimulus event is generated.

The second type of error that can occur is the call to the CICS ECI can fail for some reason (i.e., CICS may not be running on the client). When this happens, a stimulus event is generated, and the CICSGetError routine returns the return value from the ECI call.

The third type of error occurs during execution of the CICS transaction. The nature of the error that occurred is indicated by error codes in the ECIPARMS structure. When this happens, a stimulus event is generated, and you can retrieve the updated ECIPARMS structure by calling CICSGetError. (Consult the CICS documentation for more information on the meaning of these errors.)