PI57812: SUPPORT DYNAMIC STORAGE IN COBOL (PIC X(1) LINKAGE SECTION ITEMS WITH REFERENCE MODIFICATION AND TABLE ODO OVERLAYS)

Obtain the fix for this APAR.

APAR status

• Closed as program error.

Error description

• In earlier versions of COBOL, customer source frequently
  handled dynamically sized pieces of storage by using a PIC X(1)
  linkage section data-item and then reading or writing beyond
  the bounds of that array.  This APAR will add this type of
  support to COBOL V5 to make the behavior consistent with COBOL
  V4.
  
  LINKAGE Example:
  
  WORKING-STORAGE SECTION.
  01  wrk-len                 PIC s9(08) binary.
  LINKAGE SECTION.
  01  L-String1               PIC X(1).
  01  L-String2               PIC X(1).
  PROCEDURE DIVISION.
  0000-MAIN.
      MOVE 1000 TO wrk-len
      MOVE L-String1(1:wrk-len) TO L-String2(1:wrk-len)
  
  Behavior difference:  COBOL V4 moves 1000 bytes.  COBOL V5
  moves 232 bytes due to differing instructions.
  
  TABLE ODO Example:
  WORKING-STORAGE SECTION.
  01  CONTROLVAR PIC 9(5) BINARY.
  01  MYCONTAINER.
      02  MYTABLE.
          03 TBL OCCURS 0 TO 1 TIMES DEPENDING ON CONTROLVAR.
             05 MYFIELD PIC X(1).
      02 DUMMY PIC X(300).
  PROCEDURE DIVISION.
      MOVE 1 TO CONTROLVAR
      MOVE ALL 'Z' TO DUMMY
      DISPLAY DUMMY          <= Contains all Z's
      MOVE 300 TO CONTROLVAR
      MOVE ALL 'M' TO MYTABLE <= MYTABLE has 1 byte of M's in V4
      DISPLAY MYTABLE
      MOVE 1 TO CONTROLVAR
      DISPLAY DUMMY   <= DUMMY HAS 299 BYTES OF M's in V4.
  
  Behavior difference:  COBOL V4 overlays storage following
  MYTABLE exactly as expected byte for byte.  COBOL V5 handles
  the overlay differently such that the storage results differ
  from COBOL V4.
  

Local fix

Problem summary

• ****************************************************************
  * USERS AFFECTED: Users of Enterprise COBOL 5.1 compiling and  *
  *                 running programs that are compiled with the  *
  *                 OPT(1) or OPT(2) compiler options and are    *
  *                 using a variable length reference            *
  *                 modification to deliberately move data into  *
  *                 a linkage section data item beyond its       *
  *                 defined length.                              *
  *                                                              *
  *                                                              *
  ****************************************************************
  * PROBLEM DESCRIPTION: Incorrect output. The number of bytes   *
  *                      that are moved into the receiver is     *
  *                      capped at the defined length of the     *
  *                      receiver data item, which may be        *
  *                      shorter than the runtime length of the  *
  *                      reference modification in the move      *
  *                      operation. This behavior differs from   *
  *                      pre-V5 releases of the Enterprise       *
  *                      COBOLcompiler, which did not attempt    *
  *                      to cap the length of such move          *
  *                      operations.                             *
  *                                                              *
  ****************************************************************
  * RECOMMENDATION: Apply the provided PTF.                      *
  *                                                              *
  ****************************************************************
  Consider two COBOL programs, PROGA and PROGB:
  
  PROGA:
  
  DATA DIVISION.
  WORKING-STORAGE SECTION.
  01 DATA1 PIC X(100).
  PROCEDURE DIVISION.
  CALL PROGB USING BY REFERENCE DATA1
  
  PROGB:
  
  DATA DIVISION.
  WORKING-STORAGE SECTION.
  01 LEN PIC 9(5) BINARY.
  LINKAGE SECTION.
  01 DATA1 PIC X(1).
  01 DATA2 PIC X(500).
  PROCEDURE DIVISION USING BY REFERENCE DATA1.
  :
  MOVE 100 to LEN
  MOVE DATA2(1:LEN) TO DATA1(1:LEN)                      col 64->|
  
  When optimizing PROGB, the compiler was capping the length of
  the move in statement 'MOVE DATA2(1:LEN) TO DATA1(1:LEN)' to 1
  byte, which technically is the maximum length of the move based
  on the definition of DATA1 in PROGB, but this behavior is
  different from pre-V5 releases of the compiler which allowed
  users to simulate unbounded parameters using this pattern.
  

Problem conclusion

• The compiler was updated to ensure that in the above move
  scenario the runtime length of the move, as implied by the
  variable length reference modification, is always used
  regardless of the defined length of the receiving data item in
  the linkage section.
  

Temporary fix

Comments

APAR Information

• APAR is sysrouted FROM one or more of the following:

• APAR is sysrouted TO one or more of the following:

  PI59330 PI59354 PI63286

Modules/Macros

•    IGYECNTL
  

Fix information

• Fixed component name

  ENT COBOL FOR Z

• Fixed component ID

  5655W3200

Applicable component levels

• R510 PSY UI37372

     UP16/04/29 P F604

Fix is available

• Select the PTF appropriate for your component level. You will be required to sign in. Distribution on physical media is not available in all countries.