Identification token

In order for the exits to be able to relate calls for the same ECI request, an identification token is passed in as a parameter to all exits except CICS_EciInitializeExit and CICS_EciTerminateExit. The token is the same for CICS_EciExternalCallExit1 and CICS_EciExternalCallExit2 that relate to the same call, and on intervening CICS_EciDataSendExit, CICS_EciDataReturnExit, and CICS_EciSystemIdExit exits. (Note that CICS_EciExternalCallExit1 and CICS_EciExternalCallExit2 are not called for a reply solicitation request.)

The token is unique within the operating system that initiated the request, for the duration of the request. It may be reused once the last exit for the request has been called.

In the case of an extended logical unit of work, the token may be different on different requests within the logical unit of work. (Since we allow reuse of the token, and a new program link call may not be made until the ECI_GET_REPLY request for the previous asynchronous request has completed, it may also be the same.)

The token is 8 bytes long. 8 null bytes is not a valid value for the token and is not supplied to the exits.