The listener CallMonitor of JPF prints for each method that is called
- the ID of the thread that executed the call,
- the depth of the stack,
- the name of the class,
- the name of the method, and
- its arguments.

Consider the following app.

public class Example {
  public static void main(String [] args) {
    first(1, true);    
  }

  private static void first(int i, boolean b) {
    second(i + 1);
  }

  private static void second(int i) {
    System.out.println(i);
  }
}

If we run JPF with the following application configuration file

target=Example
classpath=<folder that contains Example.class>
listener=gov.nasa.jpf.listener.CallMonitor

then JPF produces output similar to the following.

JavaPathfinder core system v8.0 (rev d772dfa80ea692f916aa6718d04c4f7bfb2a746b) - (C) 2005-2014 United States Government. All rights reserved.


====================================================== system under test
Example.main()

====================================================== search started: 2/22/19 4:57 PM
2

====================================================== method invocations
0:              java.lang.Boolean.<clinit>()
...
0:   Example.main([Ljava.lang.String;@bb)
0:    Example.first(1,true)
0:     Example.second(2)
0:      gov.nasa.jpf.ConsoleOutputStream.println(2)

====================================================== results
no errors detected

====================================================== statistics
elapsed time:       00:00:00
states:             new=1,visited=0,backtracked=1,end=1
search:             maxDepth=1,constraints=0
choice generators:  thread=1 (signal=0,lock=1,sharedRef=0,threadApi=0,reschedule=0), data=0
heap:               new=350,released=11,maxLive=0,gcCycles=1
instructions:       3184
max memory:         57MB
loaded code:        classes=61,methods=1331

====================================================== search finished: 2/22/19 4:57 PM

As can be seen from the above output, all method invocations are executed by the main
thread which has ID 0.  The number of spaces following "0: " represents the stack depth.
JPF executes many method invocations before it reaches the main method.