TEST DO WHILE
%DCL LENGTH BUILTIN;
%DCL P ENTRY;
%P: PROC(X) RETURNS(CHAR);
   DCL X CHAR, I FIXED;
   DCL Y CHAR;
   Y = '';
   I = LENGTH(Y);
   DO WHILE(I<6);
      Y = Y || X;
      I = LENGTH(Y);
   NOTE('Y:'||Y,I);
   END;
   NOTE('RTRN:'||Y,I);
   RETURN(Y);
%END P;
%TRACEON;
P(AB)