Java dumps

In z/OS® UNIX, most z/OS Explorer dumps are controlled by the Java™ Virtual Machine (JVM).

The JVM creates a set of dump agents by default during its initialization (SYSTDUMP and JAVADUMP). You can override this set of dump agents using the JAVA_DUMP_OPTS environment variable and further override the set by the use of -Xdump on the command line. JVM command-line options are defined in the _RSE_JAVAOPTS directive of rse.env. Do not change any of the dump settings unless directed by the IBM® support center.

Note: The -Xdump:what option on the command line can be used for determining which dump agents exist at the completion of startup.

The types of dump that can be produced are the following:

SYSTDUMP

Java Transaction dump. An unformatted storage dump generated by z/OS.

The dump is written to a sequential MVS data set, using a default name of the form %uid.JVM.TDUMP.%job.D%y%m%d.T%H%M%S, or as determined by the setting of the JAVA_DUMP_TDUMP_PATTERN environment variable.

Note: JAVA_DUMP_TDUMP_PATTERN allows the usage of variables, which are translated to an actual value at the time the transaction dump is taken.

Table 1. JAVA_DUMP_TDUMP_PATTERN variables
Variable	Usage
%uid	User ID
%job	Job name
%y	Year (2 digits)
%m	Month (2 digits)
%d	Day (2 digits)
%H	Hour (2 digits)
%M	Minute (2 digits)
%S	Second (2 digits)

CEEDUMP

Language Environment® (LE) dump. A formatted summary system dump that shows stack traces for each thread that is in the JVM process, together with register information and a short dump of storage for each register.

The dump is written to a z/OS UNIX file named CEEDUMP.yyyymmdd.hhmmss.pid, where yyyymmdd equals the current date, hhmmss the current time and pid the current process ID. The possible locations of this file are described in z/OS UNIX dump locations.

HEAPDUMP

A formatted dump (a list) of the objects that are on the Java heap.

The dump is written to a z/OS UNIX file named HEAPDUMP.yyyymmdd.hhmmss.pid.TXT, where yyyymmdd equals the current date, hhmmss the current time and pid the current process ID. The possible locations of this file are described in z/OS UNIX dump locations.

Note that z/OS Explorer provides an operator command to trigger this dump. See the "Operator commands" chapter in the Host Configuration Guide (SC27-8437) for more details.

JAVADUMP

A formatted analysis of the JVM. It contains diagnostic information related to the JVM and the Java application, such as the application environment, threads, native stack, locks, and memory.

The dump is written to a z/OS UNIX file named JAVADUMP.yyyymmdd.hhmmss.pid.TXT, where yyyymmdd equals the current date, hhmmss the current time and pid the current process ID. The possible locations of this file are described in z/OS UNIX dump locations.

Note that z/OS Explorer provides an operator command to trigger this dump. See the "Operator commands" chapter in the Host Configuration Guide (SC27-8437) for more details.

Refer to Java Diagnostic Guide (SC34-6358) for more information on JVM dumps, and Language Environment Debugging Guide (GA22-7560) for LE-specific information.