It's exciting now that OMEGAMON Messaging V7.1 provides a robust 3270 interface. With V7.1 there are many powerful new displays inclduing the Health overview panel.
The Health Overview panel gives the overall health values for queue manager, queues and channels, and the worst health status on the display will be sorted to the top of list. Among the various values used in determining health include Queue Manager status (Is it active? Are the channel initiator and command servers active? Are there any connections?), Queue performance indicators (Are there queues with high depth? Do XMIT queues have messages? Are there messages on the DLQ? Are there get inhibited or put inhibited queues?), and Channel status (Is the percent (of max) current channels or active channels too high? Are there current channels not in running state? Are there in-doubt channels?)
There's a lot of information on the display, and it's a good place to start for problem analysis. Here's an example of the screen: