First, a “failing” job that uses high CPU should be fixed immediately. A failure shouldn’t result in high CPU usage.
You might use Management Central to monitor for high CPU usage. In iSeries Navigator, expand Management Central. Drill into Monitors-> Job. Right-click on Job and select New monitor…
You will need to experiment with a number of settings. I can’t tell you what to try on your system because I have no idea what all the possibilities are in your environment. When complete the first page, select the Metrics tab. CPU is monitored under Available metrics-> Job numeric values-> CPU percent utilization.
You can set a command to run when the level is detected. You might simply run a SNDMSG command to send yourself a message.
By experimenting with the Management Central Job monitor, you will begin to understand the complexity of trying to do it yourself.