Abend conditions and environments

Callers must be aware of the following conditions that can cause an abnormal end:

When the _exit service, BPX1EXI/BPX4EXI, is called in any environment except single task, single RB, and no linkage stack, the system issues an abend EC6. This abend ends the calling task and all of its subtasks. The subtasks receive a 442 abend. If the caller is a thread task created with the pthread_create service, the initial pthread creating task abends with a 422 abend code. All subtasks of the initial pthread creating task receive a 442 abend.
Some POSIX services are defined as always successful, yet the kernel can get program checks or other MVS™ abends. When these failures occur, the user receives an EC6 abend code.
There are SLIP traps that recognize z/OS UNIX abends as normal exec service and _exit service processing. Dumps are suppressed, and the new tasks for the exec service are created. These SLIP traps are shipped as part of IEASLP00. If your system does not use IEASLP00 as provided by z/OS®, you will need to copy the SLIP commands for EC6 and 422 abends into their SLIP command parmlib member. Otherwise, your system will generate an excessive number of dumps.
Condition codes (cc) seen by the next step in a multistep job cause an abnormal end:
- Case 1:
  1. The step invokes the C main program.
  2. The C main program invokes the exit or _exit service, specifying the return code.
  3. The return code surfaces as the step condition code.
- Case 2:
  When you return from the main program, the condition code is in R15 at the time of exit.
Signals that are not caught often cause a task to end abnormally. z/OS UNIX defines which signals generate dumps. Terminating signals that do not require user dumps have an abend code of EC6 with a reason code 0000FFxx, where xx is the signal number. Parmlib member IEASLP00 has a statement to suppress all dumps that match this profile. Terminating signals that require that a user dump be taken (if requested) have an abend code of EC6 with a reason code 0000FDxx, where xx is the signal number. Parmlib member IEASLP00 has a statement to suppress all SDUMPs that match this profile but that allow user dumps to be taken.
If a process abends while it is being debugged with ptrace by a debugger program such as dbx, the debugger may be notified of the abend. The notification occurs if the tested program's recovery calls ptrace. This is normally true for C programs, because the C runtime library establishes the necessary recovery environment to call ptrace.