Your application can monitor all operating system messages appearing on a z/OS console by using the HWIEVENT service to register for the EventIDs parameter value Hwi_Event_OpSysMsg.

For the majority of messages issued on the image being monitored, a single BCPii operating system message event will contain the entire message in the returned event data (HWIENF68 data mapping).

For messages that are larger than approximately 3000 bytes, it is possible that the operating system message is longer than the architected maximum buffer size allowed by the communications protocol used by both the z/OS consoles component and BCPii to communicate with the support element. As a result, BCPii delivers these single large messages in multiple operating system message events. Each of these operating system message events representing a single large message will have the same values in the HWIENF68 data mapping for the msgId, msgDate, and msgTime fields. An application can determine that all of the operating system message events have been delivered for the single large message by consulting the msgId of a subsequent message event. If it has changed from the previous msgId, the operating system message event represents a new operating system message.