Did you have any memory problems with your applications recently? Wild accesses, improperly initialized variables, memory leaks, illegal frees etc sounds familiar? Then you should take a look at valgrind. It's now available for Linux on System z as well in SLES10 SP4, RHEL 6.1 (version 3.6) and SLES11 SP2 (version 3.7).
There is now an in depth article for usage on Linux on System z in the latest zJournal. Besides all the description it also has an example which shows you the usage of this powerful tool.