Java™ method call traces provide significant performance information about the time that is spent in each Java method.
On other Java virtual machines, you may have used the -prof (profiling) option on the java command. To enable method call tracing on an iSeries™ server, you must specify the Enable Performance Collection (ENBPFRCOL) command on the Create Java Program (CRTJVAPGM) command line. After creating your Java program with this keyword, you can start the collection of method call traces by using a Performance Explorer (PEX) definition that includes the call/return trace type.
Call/return trace output produced with the Print Performance Explorer Report (PRTPEXRPT) command shows the central processing unit (CPU) time for each call for every Java method that is traced. In some cases, you may not be able to enable all of the class files for call return tracing. Or, you may be calling native methods and system functions that are not enabled for tracing. In this situation, all of the CPU time that is spent in these methods or system functions accumulates. Then, it is reported to the last Java method that is called and has been enabled.