PH42041: PERFORMANCE OF PACKED-DECIMAL DIVIDE GIVING REMAINDER STATEMENTS MAY BE WORSE IN COBOL 6.3 THAN IN COBOL 6.2

Obtain the fix for this APAR.

APAR status

• Closed as program error.

Error description

• PERFORMANCE OF PACKED-DECIMAL DIVIDE GIVING REMAINDER
  STATEMENTS MAY BE WORSE IN COBOL 6.3 THAN IN COBOL 6.2
  

Local fix

• None. Apply PTF
  

Problem summary

• ****************************************************************
  * USERS AFFECTED: Users of Enterprise COBOL 6.3 compiling      *
  *                 programs at ARCH(12|13) that contain DIVIDE  *
  *                 GIVING REMAINDER statements where the        *
  *                 divisor is PIC 9(5) or smaller.              *
  ****************************************************************
  * PROBLEM DESCRIPTION: Performance is worse with COBOL 6.3     *
  *                      than COBOL 6.2.                         *
  ****************************************************************
  * RECOMMENDATION: Apply the provided PTF                       *
  ****************************************************************
  z14 introduces vector packed decimal instructions, allowing
  packed decimal operations to be done natively in registers.
  On z14/z15 (ARCH(12|13)), Enterprise COBOL was generating a
  divide with remainder sequence using a VDP instruction to do
  the division, and then a VMP and VSP to compute the remainder
  by multiplying the quotient by the divisor and subtracting that
  from the dividend. At lower ARCH levels, the same operation was
  done with the DP instruction; while that operated on the
  dividend and divisor in memory, instead of registers, it also
  computes both the remainder and quotient at once. Despite the
  extra steps, the vector packed instructions are faster than a
  DP except in the case where the divisor is 5 digits or less.
  However, COBOL 6.3 was always choosing to use a VDP regardless
  of the size of the divisor.
  

Problem conclusion

• While the exact value of the divisor can't usually be known at
  compile time, and so a divisor with a large number of digits in
  the picture clause could still contain a small value, divisors
  with picture clauses of 5 or less must always contain a value
  that's 5 digits or less. The compiler was fixed to use a DP in
  cases where the divisor has a picture clause of 5 or fewer
  digits, as in those cases, it is always faster to use a DP than
  a VDP
  

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

• IGY8RWTU IGYCASMB IGYCCBE  IGYCCCRT IGYCCICS IGYCCSRV IGYCDGEN
  IGYCDIAG IGYCDMAP IGYCEN$0 IGYCEN$1 IGYCEN$2 IGYCEN$3 IGYCEN$4
  IGYCEN$5 IGYCEN$8 IGYCEN$D IGYCEN$R IGYCFGEN IGYCFREE IGYCINIT
  IGYCJA$0 IGYCJA$1 IGYCJA$2 IGYCJA$3 IGYCJA$4 IGYCJA$5 IGYCJA$8
  IGYCJA$D IGYCJA$R IGYCLIBR IGYCLSTR IGYCLVL0 IGYCLVL1 IGYCLVL2
  IGYCLVL3 IGYCLVL8 IGYCMALL IGYCOSCN IGYCPGEN IGYCRCTL IGYCRDPR
  IGYCRDSC IGYCREAL IGYCRWT  IGYCSCAN IGYCSIMD IGYCUE$0 IGYCUE$1
  IGYCUE$2 IGYCUE$3 IGYCUE$4 IGYCUE$5 IGYCUE$8 IGYCUE$D IGYCUE$R
  IGYCXREF IGYDRV   IGYEQCWI IGYMSGE  IGYMSGK  IGYMSGT  IGYQCBE
  IGYQSPLT IGYZQEN6 IGYZQENU IGYZQJP6 IGYZQJPN
  

Fix information

• Fixed component name

  ENT COBOL FOR Z

• Fixed component ID

  5655EC600

Applicable component levels

• R630 PSY UI78163

     UP21/11/25 P F111

• R631 PSY UI78164

     UP21/11/25 P F111

• R632 PSY UI78165

     UP21/11/25 P F111

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.