CLEAR                    Close Files, Reset Variables, Set Stack Space

 CLEAR [,,stack]

    Closes all files, clears all COMMON variables, resets all numeric
    variables to 0 and all string variables to null, releases all disk
    buffers, resets the stack, and optionally specifies the size of the
    stack.

       stack    Specifies, in bytes, the size of QuickBASIC's stack. The
                default is 768 bytes; the minimum is 512 bytes.

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      Notes:    CLEAR destroys pending return addresses left on the stack
                by GOSUB, FOR/NEXT, and WHILE/WEND.

                CLEAR does not affect symbolic constants.

                QuickBASIC's CLEAR differs from the Interpreter's in two
                ways:

                1.  The Interpreter's CLEAR statement destroys all DEF FN
                    and DEFtype statements. QB's does not.

                2.  The interpreter's default stack is 512 bytes. QB's is
                    768.