VERBEXIT IEFENFVX subcommand — list ENF listeners

Specify the IEFENFVX verb name on the VERBEXIT subcommand to format a list of Event Notification Facility (ENF) listeners.

Parameters
The VERBEXIT IEFENFVX subcommand has one optional parameter: an ENF event code.
Examples:
- To obtain a list of ENF listeners for all the event codes:
```
VERBEXIT IEFENFVX
```
- To obtain a list of ENF listeners for an event code 4:
```
VERBEXIT IEFENFVX    '4'
```