PI31403: PROBLEM MIGRATING PROGRAMS WITH INVALID ZONE BITS TO COBOL V5.x FROM COBOL V4.2.

Obtain the fix for this APAR.

APAR status

• Closed as program error.

Error description

• Customer found that they had blanks inside of USAGE DISPLAY
  numeric data (zoned decimal data) so that comparing to ZERO was
  true (4 is not a valid zone code):
      77  VALUE0    PIC X(4) VALUE '00 0'.     <*  x'F0F040F0'
      77  VALUE1    REDEFINES VALUE0 PIC 9(4).           ^
      IF VALUE1 = ZERO
        DISPLAY ?COBOL V4 (or earlier) with NUMPROC(MIG) and V5
               with OPT(0)'
      ELSE
        DISPLAY ?COBOL V4 with NUMPROC(NOPFD or PFD) and also
                ? COBOL V5 with OPT(1) or OPT(2) in effect
      END-IF
  If users have such invalid zone codes in their zoned decimal
  data and do numeric compariosons with such data items, they
  could get different results with COBOL V5.x.
  Best approach for the users is to fix their invalid data. The
  more practical approach to accommodate migration to Enterprise
  COBOL V5.x is to use a new compiler option ZONEDATA.
  

Local fix

• N/A
  

Problem summary

• ****************************************************************
  * USERS AFFECTED: Users of Enterprise COBOL V5 migrating from  *
  *                 earlier COBOL compilers when there are       *
  *                 invalid zone bits in USAGE DISPLAY numeric   *
  *                 (zoned decimal) data items that are also     *
  *                 used in numeric comparisons                  *
  *                                                              *
  ****************************************************************
  * PROBLEM DESCRIPTION: Numeric comparisons get different       *
  *                      results in COBOL V5 with OPT(1 or 2).   *
  *                      If users recompile programs that have:  *
  *                       - USAGE DISPLAY numeric data items     *
  *                         that contain bad zone bits and have  *
  *                       - numeric comparisons using such data  *
  *                         items                                *
  *                                                              *
  ****************************************************************
  * RECOMMENDATION: Apply the provided PTF.                      *
  *                                                              *
  ****************************************************************
  The compiler was assuming that the zone bits were valid so
  that comparisons could be done with instructions that were
  optimized to string compares rather than instructions to convert
  to numeric and do numeric compares in relation conditions.
  

Problem conclusion

• The compiler was changed to add a new compiler option to address
  this challenge.  This APAR adds the ZONEDATA(PFD|MIG) compiler
  option.  With ZONEDATA(MIG), COBOL V5 will behave like
  COBOL V4 for the above narrow case.  This will be true
  regardless of OPT setting.  Here are changes to the Programming
  Guide and Customization Guide for this new compiler option:
  +--------------------------------------------------------------+
  | Start of changes for:                                        |
  | Enterprise COBOL for z/OS Programming Guide, SC14-7382-01    |
    Chapter 17:  Compiler options
     Add the ZONEDATA compiler option between XREF and ZWB:
    ZONEDATA(PFD|MIG)
    This compiler option tells the compiler whether USAGE DISPLAY
    numeric data items(zoned decimal) will contain data with
    valid zone bits (PFD) or may contain data with invalid zone
    bits (MIG) for numeric comparisons.
                       +--PFD--+
                       |       |
      >>---ZONEDATA--(-+--MIG--+-)--->>
   Default: ZONEDATA(PFD)
   Abbreviations:  ZD
   Each digit of a valid zoned decimal number is represented by a
   single byte X'F0' through X'F9'. The 4 high-order bits of each
   byte are zone bits . The 4 low-order bits of each byte contain
   the value of the digit. The 4 high-order bits of the low-order
   byte (for SIGN TRAILING) represent the sign of the item.
   The sign is in the high-order byte with SIGN LEADING, or in a
   separate byte for SIGN IS SEPARATE.
   When ZONEDATA(MIG) is in effect, the compiler will generate
   instructions to do numeric compares that will ignore the zone
   bits of each digit in zoned decimal data items. For example,
   if the zoned decimal value is converted to packed-decimal
   with a PACK instruction prior to the compare.
   Note1: The sign zone must still be a valid sign according to
          the NUMPROC zompiler option setting.
   Note2: For unsigned and for sign is separate, the last zone
          must also have correct zone bits
   When ZONEDATA(PFD) is in effect, the compiler will assume that
   the zone bits in zoned decimal data items are valid, and
   generate the most efficient code possible to make the
   comparison.  For example, it might generate a string compare
   to avoid numeric conversion.
   Example:
  ***************************************************************
  *  In this example we use a data item with a bad zone code
  *  '4' in the zone bits in the middle of data item VALUE1,
  *  forced in via REDEFINES
  ***************************************************************
   77  VALUE0    PIC X(4) VALUE '00 0'.     <*  x'F0F040F0''
   77  VALUE1    REDEFINES VALUE0 PIC 9(4).           ¼
   PROCEDURE DIVISION..
  ***************************************************************
  *  In this example the test is true in COBOL V4 and earlier
  *  if the NUMPROC(MIG) option was used, and FALSE for other
  *  NUMPROC settings.
  *  In COBOL V5.1 before the ZONEDATA option was added, the
  *  test was true at OPT(0) and false at OPT(1|2).  With
  *  ZONEDATA(MIG) the test will be TRUE at any OPT setting.
  ***************************************************************
       IF VALUE1 = ZERO
          DISPLAY 'ZONEDATA(MIG) is in effect ' VALUE1
       ELSE
          DISPLAY 'ZONEDATA(PFD) is in effect '  VALUE1
       END-IF
   ZONEDATA(MIG) can help migration to COBOL V5 for customers
   who have:
    - USAGE DISPLAY numeric data items that contain bad zone
      bits at run time and
    - numeric comparisons using such data items and
    - been compiling with the NUMPROC(MIG) compiler option.
   In such cases, ZONEDATA(PFD) can give different results for
   comparisons using USAGE DISPLAY numeric data items than the
   previous compiler.  Customers can either correct their data
   or use ZONEDATA(MIG).
   ZONEDATA(MIG) will have worse runtime performance than
   ZONEDATA(PFD).
   ZONEDATA(MIG) will disable some of the optimizations that
   NUMPROC(PFD) could give.
  | End of changes for:                                          |
  | Enterprise COBOL for z/OS Programming Guide, SC14-7382-01    |
  +--------------------------------------------------------------+
  +--------------------------------------------------------------+
  | Start of changes for:                                        |
  | Enterprise COBOL for z/OS Customization Guide, SC14-7380-01  |
    Chapter 2:  Enterprise COBOL compiler options
     Add the ZONEDATA compiler option between XREF and ZWB.  Use
    the same descriptions as the Programming Guide except for
    different syntax:
                             +--PFD--+
                             |       |
      >>---ZONEDATA=--+---+--+--MIG--+---->>
                      |   |
                      +-*-+
     Default: ZONEDATA=PFD
     Abbreviations:  None
  | End of changes for:                                          |
  | Enterprise COBOL for z/OS Customization Guide, SC14-7380-01  |
  +--------------------------------------------------------------+
  

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:

Modules/Macros

•    IGYCDOPT IGYCOPI  IGYCOPT  IGYKCNTL IGYKSTAT
  IGYWINIT
  

Fix information

• Fixed component name

  ENT COBOL FOR Z

• Fixed component ID

  5655W3200

Applicable component levels

• R510 PSY UI24300

     UP15/01/15 P F501

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.