Problem Statement

Show the syntax for a complete stoppage of a program inside a   conditional. This includes all threads/processes which are part of your program. Explain the cleanup (or lack thereof) caused by the termination (allocated memory, database connections, open files, object finalizers/destructors, run-on-exit hooks, etc.).
Unless otherwise described, no special cleanup outside that provided by the operating system is provided.

Let's start with the solution:

STOP; /* terminates the entire program */
      /* PL/I does any required cleanup, such as closing files. */

STOP THREAD (tiger); /* terminates only thread "tiger". */

SIGNAL FINISH; /* terminates the entire program.   */
               /* PL/I does any required cleanup,  */
               /* such as closing files.           */