Problem with relative file

Hi,
Has anybody seen such a problem on Iseries. We have a CL which calls the
cobol program , in the CL we create a file with following command
CRTPF XXLIB/XXFILE RCDLEN(250)
OVRDBF F05TRAV TOFILE(XXLIB/XXFILE)
CALL COBOLXYZ

In the Cobol program COBOLXYZ we have following defination for the file
SELECT F05TRAV ASSIGN TO DATABASE-F05TRAV 
       ORGANIZATION IS RELATIVE           
       ACCESS MODE IS RANDOM              
       RELATIVE KEY IS F05-KEY.           

And just  before opening of file the code we call to a CL to do a CLRPFM
on file XXLIB/XXFILE (I know it is not required but we have done it as
this is a generic customer requirement)

And then we have following code
OPEN OUTPUT F05TRAV.                     
CLOSE       F05TRAV.
OPEN I-O    F05TRAV.

The problem is that as soon as the code reaches point where we do OPEN
OUTPUT F05TRAV the size of file XXLIB/XXFILE starts increasing at a
phenomenal rate and it eats all the disk space and there is no way to
end the job , only solution is a PWRDWNSYS. 


Please suggest if you have seen this problem earlier.
The Iseries is running V5R2M0.

Regards
Aseem