Figure 1 illustrates how z/OS UNIX determines if a signal is enabled, ignored, or blocked. A few POSIX signals do not go through this process. See POSIX signals that do not enter condition handling for details.
If a signal is ignored or blocked, the signal does not enter Language Environment synchronous condition handling. If a signal is enabled, z/OS UNIX passes it to the Language Environment enablement step (described in Enablement step). From there, Language Environment either disables the signal, or passes it into the Language Environment condition step.