public Parser callStatement() {
        if (callStatementParser == null) {
           FutureParser future = scoped("callStatement");
           callStatementParser = future;
           future.setParser(
               sequence(
                   token("CALL"),
                   choice(
                       token("NESTED"),
                       sequence(
                           mnemonicName(),
                           choice(
                               alphanumericLiteral(),
                               identifier()
                           )
                       ),
                       sequence(
                           choice(
                               alphanumericLiteral(),
                               identifier()
                           ),
                           optional(
                               sequence(
                                   token("AS"),
                                   choice(
                                       token("NESTED"),
                                       programName()
                                   )
                               )
                           )
                       )
                   ),
                   optional(
                       callUsing()
                   ),
                   optional(
                       callGivingOrReturning()
                   ),
                   optional(
                       choice(
                           onOverflow(),
                           sequence(
                               onException(),
                               optional(
                                   notOnException()
                               )
                           ),
                           notOnException()
                       )
                   ),
                   optional(
                       token("END-CALL")
                   )
               )
           );
        }

        return callStatementParser;
    }