Dump

A dump is a snapshot of memory taken when something fails. It shows what was in the program's storage, which instruction was running, and the state of the registers at that moment. It is evidence for working out what went wrong after the program has gone.

There are several kinds. Adding a SYSUDUMP or SYSABEND DD statement to a job step asks for a readable dump in the job output if the step abends. Programs that run under Language Environment, such as COBOL programs, can also produce a CEEDUMP: a shorter report that shows where the program failed and, with the right compile options, the values of its variables. The system itself can take large dumps of whole address spaces, which system programmers read with a tool called IPCS.

For an application developer, the most useful facts in a dump are the abend code and where the failure happened. With the compile listing, you can usually turn the failing address into a line of source code.

Dumps can contain sensitive data, such as customer records that were in memory, so sites control who can read them.