When a CLIST is executed, it translates each statement into an executable format and places it in a section of storage called the input stack. The input stack is the source from which TSO/E obtains its input (TSO/E commands, CLIST statements).

If you write a CLIST that contains an error routine, protect the input stack from being erased from storage (flushed) when an error occurs. You can protect the input stack by coding a CONTROL statement that includes the NOFLUSH or MAIN operand. The CONTROL statement must appear before any error routine, preferably at the beginning of the CLIST.