A signal callback is called whenever a process receives a signal on a UNIX platform.
On UNIX platforms, Client-Library uses signal-driven I/O to interact with the network. On these platforms, if an application handles signals, it must install the signal handler through Client-Library, even if the signals relate to non-Client-Library work. To install a signal handler, call ct_callback instead of using a system call. A system call to install a signal handler overwrites Client-Library’s signal handler. If this occurs, Client-Library behavior is undefined.
When Client-Library is used in an Open Server gateway, signal handlers should be installed using Server-Library routines.
When Client-Library receives the Client-Library signal handler:
Performs any internal Client-Library processing that is required
Calls the appropriate user-defined signal callback, if any
