Optimizer Options

When the Natural Optimizer has been activated, you can specify checks by setting the options explained in this section.

The options cannot be used for specifying statements to be optimized.

This Dokument covers the following topics:


List of Options

The following table lists and describes the Natural Optimizer Compiler options. Default values are underlined (this is the value that will be assumed if the option is not present).

A Natural Optimizer Compiler option consists of a string surrounded by brackets or single quotation marks (except in the Natural OPTIONS statement), with options separated by commas. Some options have values, while the very existence of some options in the option string is sufficient to modify the environment.

The following rules apply:

  • Optional clauses are surrounded by square brackets [ ].

  • Choices are surrounded by curly braces { }.

  • Each choice is separated by vertical lines "|".

  • Only one of these choices can be specified;

    ON is equivalent to Y (Yes),

    OFF to N (No).

  • Options specified without the optional clause ON or OFF (if applicable), or their equivalent values, are interpreted as set to ON. For example, OVFLW is identical to OVFLW=ON.

  • Except for the option OFF, any specified option switches on optimizing (as if ON was specified) and the default values apply. For example, INDEX is identical to ON,INDEX.

Option Explanation
ABEND Forces the Natural Optimizer Compiler to generate code which causes Natural to be abnormally terminated immediately when the ABEND option is encountered by the Natural Optimizer Compiler during compilation. The option must appear by itself or it will be ignored. Other parameters are not changed or reset by this option. This option can be useful for debugging purposes.
ARCH Specifies the architecture level to be used for code generation: see ARCH Option in the following section.
ARROPT Specifies the generation to be used for array assignments of the type A(*):=scalar. See ARROPT Option in the following section.
CACHE[={ON| OFF |Y|N}] Switches variable caching on or off. See also Variable Caching in the section Performance Considerations.
CPU= /370 Specifies the target architecture.
DIGTCHCK[={ON| OFF |Y|N}] Specifies whether the digits of packed and unpacked numeric fields (formats P and N) are to be checked when moving to another variable of the same type and precision. For example, if DIGTCHCK is ON and an unpacked numeric variable (format N) contains an invalid digit, such as X'FA', moving to another unpacked numeric variable with the same precision will generate a S0C7 (or NAT0954) error. If DIGTCHCK is OFF, no error is generated but the generated code is much faster.
ERRDUMP[={ON| OFF |Y|N}] Specifies whether NOC should abend if an error condition is detected during the compile phase. This is useful for debugging the Natural Optimizer Compiler itself.
INDEX[={ON| OFF |Y|N}] Specifies whether array indexes will be checked for out-of-bound values in the optimized code.

See also the following Note.

INDX[={ON| OFF |Y|N}] Specifies whether array indexes will be checked for out-of-bound values in the optimized code.

Additionally, RANGE will be set on. Therefore, this option is equivalent to INDEX=ON,RANGE=ON.

See also the following Note.

IO[={ON| OFF|Y|N}] Provided for compatibility reasons only. No effect.
LOOPS[={ON| OFF |Y|N}] Provided for compatibility reasons only. No effect.
MIX[={ON| OFF |Y|N}] Provided for compatibility reasons only. No effect.
NODBG[={ON| OFF|Y|N}] If NODBG=OFF/N (default), the Natural Debugger can be used to debug optimized code (then, additional code is generated to check whether TEST mode has been set on).

If NODBG=ON/Y, less code will be generated, the program will run faster and consume less CPU time. On the other hand, the functionality of the Natural Debugger will be limited, because the Natural Debugger might not receive control for optimized statements.

See also NODBG in the section Performance Considerations.

NOSGNTR[={ON| OFF |Y|N}] Applies to packed numbers only.

If NOSGNTR=OFF (default), signs of positive packed numbers which are the result of an arithmetic operation or the target of an assignment are set according to the COMPOPT parameter PSIGNF. If NOSGNTR=ON, the signs resulting from execution of the generated machine instruction are left unchanged. See also the section Influence of other Natural Parameters.

ON Switches on optimizing. If no additional option is specified, the default value defined for each option is in effect. As indicated in the following Note, this may cause unintended results, in particular regarding the options INDEX, INDX, OVFLW, and RANGE.
OFF Switches off optimizing.
OPTLEV={ 2|3} Specifies optimization level - roughly equivalent to the number of passes through the program.

OPTLEV=3 is useful when PGEN is specified, since some branch targets cannot be determined during the first pass and PGEN output is made during the last pass. Thus, some values may be shown improperly.

OVFLW[={ON| OFF |Y|N}] Specifies whether checks for overflow in arithmetic operations or assignments will be included in the optimized code.

See also the following Note.

PGEN[={ON| OFF |Y|N}] Specifies whether a disassembly of the optimized code should be output. This option also enables all other tracing options: see PGEN Option in the following section.
RANGE[={ON| OFF |Y|N}] Specifies whether range checks will be performed in operations with arrays. This ensures that array ranges will have an equal number of elements in corresponding dimensions of all operands.

See also the following Note.

SIGNCHCK[={ ON|OFF|Y|N}] Specifies whether the result of a multiplication with a packed or unpacked numeric multiplier should be checked for a negative zero. If zero is multiplied by a negative number, the MP machine instruction generates a negative zero result. If SIGNCHCK is on, this negative zero is converted to a positive zero. The check for a negative zero is done for every multiplication with a packed or unpacked numeric multiplier.
TRENTRY For internal use by Software AG only. Do not change the setting of this parameter.
UNICC Specifies whether optimized code is generated for IF and DECIDE statements with Unicode operands: see UNICC Option in the following section.
ZD[={ ON|OFF|Y|N}] Specifies whether divisors should be checked for zero. If this option is specified, then code is inserted, so that the program behaves according to the ZD profile parameter of Natural, that is, Natural error NAT1302 is issued or the result is zero. If this option is not specified, Natural error NAT0954 occurs if the divisor is zero.

See also ZD - Zero-Division Check in the Natural Parameter Reference documentation.

Note for INDEX, INDX, OVFLW and RANGE:

If the option INDEX, INDX, OVFLW or RANGE is set, extra instructions are added to the generated code to detect data overflow and index-out-of-range situations should they occur during program execution. Although the use of these options slightly increases the generated code, we recommend to use them to guarantee that erroneous programs are detected and cannot lead to unpredictable results, storage corruptions or abnormal program terminations.

Below is information on:

Example of INDEX and OVFLW

DEFINE DATA LOCAL
...
1 P1 (P1/9)
...
1 P3 (P3/9)
...
1 I (I4)
1 J (I4)
1 K (I4)
1 L (I4) 
END-DEFINE
...
P1(I:J) := P3(K:L)
...
END

Explanation of Example

With INDX=ON or INDEX=ON set, code is generated to verify that I, J, K and L are within the ranges defined for P1 and P3 respectively.

With INDX=ON or RANGE=ON set, code is generated to verify that I:J and K:L denote ranges of the same length.

With OVFLW=ON set, code is generated to verify that the value of P3 fits into the corresponding P1 variable.

For example: Value 100 would cause an overflow here.

Example Error Situation:

If one of the occurrences of P3 contains the value 100, with OVFLW=OFF set, the value assigned to the corresponding P1 occurrence will be zero. If the index variable I is zero or greater than 9, with INDX=OFF set, storage areas that do not belong to Array P1 will be corrupted. If these options (OVFLW and INDX) are set to ON, a Natural error occurs like it does in standard Natural runtime.

For the NOC option specified above, additional code is generated. However, this is well compensated for by the advantage of a check that, for example, protects against hard-to-debug errors. Undetected errors can, of course, lead to unpredictable results.

Optimum Code Generation

To assure that the least amount of code is generated and thus achieve optimum performance, use:

OPT='NODBG,NOSGNTR,SIGNCHCK=OFF,ZD=OFF'

However, only apply this setting to objects that have been thoroughly debugged; see also Note for INDEX, INDX, OVFLW and RANGE.

ARCH Option

The ARCH option specifies the hardware architecture level to be used for generating code for executable Natural objects.

When you specify an ARCH value, the Natural Optimizer Compiler generates newer and faster machine instructions that can improve the performance of the generated code. You cannot specify a value that is higher than the architecture level of your current machine. An executable Natural object cataloged with an ARCH level can only run on a machine with the same or a higher architecture level. Therefore, we recommend not to use the ARCH option if the cataloged objects are intended to execute on any machine, especially on a machine with a lower architecture level.

For detailed information on architecture levels, see the related literature from IBM (z/Architecture, Principles of Operation).

The following architecture levels are supported by the ARCH option of the Natural Optimizer Compiler:

Architecture Level IBM Hardware Facility Required
0 Specifies that no architecture level is used. This is the default setting for compatibility with all mainframe platforms supported by Natural.
1 to 4 These values are not evaluated and treated as ARCH=0.
5 to 6
  • z800 or z900
    Extended-Translation Facility 2

  • z890 or z990
    HFP Multiply-and-Add/Subtract Facility

7
  • z9 to z109
    Extended-Immediate Facility

8
  • z10
    General-Instructions-Extension Facility

  • z10
    Execute-Extensions Facility

9
  • zEnterprise 196
    Load/Store-on Condition Facility
    Floating-Point-Extension-Facility
    Distinct-Operands Facility
    High-Word-Facility

10
  • zEnterprise EC12 (zEC12)
    Decimal Floating-Point Facility
    Decimal Floating-Point Zoned-Conversion Facility

11
  • zEnterprise z13
    Decimal Floating-Point Packed-Conversion Facility

Anmerkung:
With an ARCH value greater zero, the Natural Optimizer Compiler generates instructions up to the facility level described in the table above. An ARCH value higher than the architecture level of the underlying machine is rejected at compile time. The attempt to start a program compiled with an ARCH level on a machine with a lower architecture level, causes a NAT1394 runtime error. You can display information on the current machine by using the TECH system command.

This Abschnitt covers the following topics:

Support for Architecture Level 10

When ARCH=10 is set, the Natural Optimizer Compiler generates instructions provided by the Decimal-Floating-Point (DFP) Zoned-Conversion Facility for the numeric operations described in the following section. This can significantly improve the execution speed for statements that use these operations.

Operations Optimized by ARCH=10

The following arithmetic operations on variables of the Natural data formats I (integer), N (numeric unpacked) and P (packed numeric) benefit from ARCH=10:

  • Value assignments:

    P:=I

    P:=N

    N:=I

    N:=N

    N:=P only if the number of packed digits is less than or equal to 15.

    I:=N

  • Arithmetic operations, such as ADD, SUBTRACT, DIVIDE and MULTIPLY statements, but only if both of the following conditions apply:

    At least one of the operands used is in the format N or I.
    The operation result does not exceed 34 (integer + precision) digits.

  • Comparisons, such as IF and DECIDE statements, but only if both of the following conditions apply:

    At least one of the operands used is in the format N.
    Both operands are in different formats.

Support for Architecture Level 11

When ARCH=11 is set, the Natural Optimizer Compiler uses machine instructions introduced with the DFP Packed-Conversion Facility. In addition to the numeric operations optimized with ARCH=10, ARCH=11 also optimizes operations that use packed variables only.

Compatibility for Architecture Level 10 and higher

When ARCH=10 is used, the Natural Optimizer Compiler generates machine instructions introduced with the Decimal-Floating-Point (DFP) Zoned-Conversion Facility, DFP Packed-Conversion Facility or the Vector Packed-Decimal Facility (VPD). These instructions execute faster than the standard machine code instructions for arithmetic operations, but they do not accept data which is improper in terms of the zoned numeric data type (N).

This may cause runtime errors, when an N-field is defined within a REDEFINE section of an alpha or binary variable and the N-field is not properly initialized before used in an arithmetic operation.

A numeric zoned field carries one digit in one byte. Usually, each byte contains x’F’ in the left halfbyte (Zone bits) and the digit value (0-9) in the right halfbyte (Numeric bits). This applies for all bytes, except for the last one, which contains (A-F) in the left halfbyte (Sign bits).

A sign halfbyte (C,A,F,E) represents a positive value, whereas (B,D) stands for a negative value. A value other than (0-9) inside the numeric halfbytes (N) and a value other than (A-F) inside the sign halfbyte (S) is considered invalid. The data inside the zone halfbytes (Z) is not regarded by arithmetic conversion instructions and can have any value (0-F).

Example for a variable defined as (N6):

ZN ZN ZN ZN ZN SN Sign is Value is Works with ARCH<=9 Works with ARCH>=10
F1 F2 F3 F4 F5 F6 F=positive 123456, ok yes yes
F3 F2 F6 F3 F3 D2 D=negative 323662, ok yes yes
40 40 40 40 40 40 4=invalid 000000, ok yes NAT7024
00 00 00 00 00 00 0=invalid 000000, ok yes NAT7024
12 13 14 15 16 17 1=invalid 234567, ok yes NAT7024
51 6B 72 7A 12 F1 F=positive 1B2A21, invalid NAT0954 NAT7024

When ARCH=9 (or lower) is used, invalid sign halfbytes (0-9) are automatically corrected by the generated code to a positive sign (F). This turns N-fields with a blank contents into valid data with value zero. The same applies for Hexa zero data.

When ARCH=10 (or higher) is used, invalid sign halfbytes (0-9) remain unchanged and lead to a program check (Data exception) when accessed by a DFP or VPD instruction. If such an abend occurs, Natural issues a NAT7024 error instead of a NAT0954 to clearly indicate that the error is caused by an N-variable that does not contain valid numeric data.

If a numeric halfbyte (N) contains a value other than (0-9), a program check (Data exception) happens regardless of the ARCH level used.

Conclusion:

Do not use ARCH=10 (or higher) to catalog a program which operates unclean numeric data, with a sign value other than (A-F).

For example:

OPTIONS MCG=(PGEN,ARCH=9)                                          
DEFINE DATA LOCAL                                                  
1 #A (A6)                                                          
1 REDEFINE #A                                                      
  2 #N (N6)                                                        
END-DEFINE                                     /*  ARCH=9  ARCH=10 
#A := H'F1F2F3F4F5F6'   ADD 1 TO #N  WRITE #N  /*  ok       ok     
#A := H'F3F2F6F3F3D2'   ADD 1 TO #N  WRITE #N  /*  ok       ok     
#A := H'404040404040'   ADD 1 TO #N  WRITE #N  /*  ok       NAT7024
#A := H'000000000000'   ADD 1 TO #N  WRITE #N  /*  ok       NAT7024
#A := H'121314151617'   ADD 1 TO #N  WRITE #N  /*  ok       NAT7024
#A := H'516B727A12F1'   ADD 1 TO #N  WRITE #N  /*  NAT0954  NAT7024
END

Moreover, when ARCH=10 (or higher) is used, Natural can issue a NAT1305 (truncated numeric value) instead of a NAT1301 error (intermediate result too large) for the following reason: The DFP or VPD numeric format is used for calculating intermediate results and an overflow is only detected at the end of the arithmetic operation when the DFP is converted into the format of the result.

ARROPT Option

The ARROPT option determines the generation algorithm to be used for array assignments of the type A(*):=scalar.

Valid values for ARROPT are:

Value Explanation
ON Recommended setting for arrays with a minimum of 50 occurrences.

ON is the default setting.

OFF Recommended setting for arrays with less than 50 occurrences.

PGEN Option

The PGEN option causes the Natural Optimizer Compiler to output the generated code and internal Natural structures. Thus, code and structures can be examined, for example, for bug fixing, performance review and support issues.

An understanding of IBM's /370 assembler is required to interpret the results produced by the PGEN option.

We recommend that you use this option with the assistance of your local Software AG representative.

Below is information on:

Setting PGEN

To use the PGEN facility, set the PGEN option when activating on the Optimizer Compiler.

Since the buffer is kept in memory, it is possible that the user thread will not be big enough to hold the trace information. In this case, try setting PGEN on only for the portion of the program which is to be traced, for example:

OPTIONS MCG=(PGEN=ON,TRGPT=ON)
or
OPTIONS MCG=+PGEN,TRGPT
Turns tracing on, including tracing of the GPT entries
OPTIONS MCG=(PGEN=OFF)
or
OPTIONS MCG=-PGEN
Turns tracing off

Various options affect the content of the output. The basic PGEN option causes a formatted listing of Natural source lines and a disassembly of the corresponding code to be generated and kept in memory for extraction by the NOCSHOW utility as described below, under Output of the PGEN Option.

The TRSTMT, TRGPT, TRMPT and TRVDT options cause hex dumps of internal data structures associated with each line to be output.

The TRBASES and TRCACHE options cause information on base registers and cache variables to be printed out. 

Sub-Options of the PGEN Option

The following table describes the options when PGEN=ON. For an explanation of the syntax used see the introduction to List of Options above.

Option Explanation
LPP={5|..| 55 |..|255} Lines-per-page for the trace output, only used when TREXT=ON.
NOsrcE[={ON| OFF |Y|N}] If NOsrcE=OFF, the Natural source statement is included in the output.
TRACELEV={ 0 |..|255} Specifies the trace level. Each bit in this one byte value specifies a buffer type to trace; these bits can be set on by using the TRxxx options as well.
TRBASES[={ON| OFF |Y|N}] Specifies whether base register allocations are traced.
TRCACHE[={ON| OFF|Y|N}] Specifies whether CACHE entries are traced.
TREXT[={ON| OFF |Y|N}] If TREXT=ON, trace is directed to the user exit NOCPRINT as described below.
TRGPT[={ON| OFF |Y|N}] Specifies whether GPT entries are traced.
TRMPT[=ON| OFF |Y|N}] Specifies whether MPT entries are traced.
TRSTMT[={ON| OFF |Y|N}] Specifies whether STMT entries are traced.
TRVDT[={ON| OFF |Y|N}] Specifies whether VDT entries are traced.

See also the examples below.

Output of the PGEN Option

There are two places to where the Natural Optimizer Compiler can direct the output of PGEN:

Internal Buffer

The contents of this buffer is overwritten each time a CHECK, CAT, STOW or RUN command is executed. A system utility NOCSHOW is provided whereby the contents of this buffer can be viewed, searched or printed.

Beginn der AnweisungslisteTo invoke the NOCSHOW utility

  • Enter the direct command NOCSHOW after a CHECK, STOW, CAT or RUN where the Natural Optimizer Compiler has been active. 

The following PF keys are available on the screen:

PF Key Function
PF2 Position to top of output
PF4 Position one line backward
PF5 Position one line forward
PF6 Print to report (1)
PF7 Position one page backward
PF8 Position one page forward
PF9 Print via Entire Connection to report (7)
PF10 Scan for text string
PF11 Repeat scan

User Exit NOCPRINT

If TREXT=ON is specified, the Natural Optimizer Compiler passes every output line to the user exit NOCPRINT instead of adding it to the trace buffer.

NOCPRINT is invoked following normal OS register conventions. Register 1 points to a full word containing the address of the 81 byte print line with ANSI carriage control characters in position 1. Register 13 points to an area of 18*4 bytes which may be used as a save area. Register 14 contains the return address and Register 15 contains the entry address of NOCPRINT.

The user exit NOCPRINT can be written in any language which supports the register conventions described above. It must be linked to the Natural nucleus together with the Natural Optimizer Compiler nucleus.

Working with the PGEN Output

This section provides hints and explanations on how to interpret the output created with the PGEN option.

  • At the top of the PGEN output are some disassembled lines which do not appear to belong to any source line. These are the instructions which make up the prologue, which is executed whenever control passes from non-optimized to optimized code. Permanent base registers are loaded and control is passed to the correct point in the prologue. See Example Section A below.

  • Sometimes a lot of source lines are printed without any code. This is because the Natural compiler puts a single line number in the object of statements which may span more than one line. See Example Section B below.

  • If the NODBG=OFF (default) has been specified, a sequence of instructions is generated at the start of each Natural statement:

    BALR R9,R11
    DC X'....'

    This sequence sets the line number (in case of error) and checks whether the TEST mode is switched ON. Without this sequence, debugging of NOC-compiled statements by the Natural Debugger is not possible. See Example Section C below.

  • Sometimes there is a line break between disassembled lines. This break indicates an internal statement separation. It happens because often a single Natural statement will generate multiple internal (pseudo-code) statements.

Example Section A:

   000000 5880 D354           L     R8,RTADR+4
   000004 5870 D370           L     R7,RTADR+32
   000008 4810 6006           LH    R1,6(,R6)
   00000C 1F60                SLR   R6,R0
   00000E 47F1 A000           BC    15,0(R1,R10)

Example Section B:


    0010 OPTIONS MCG=(PGEN=ON,TRGPT=ON)  
    0020 DEFINE DATA LOCAL
    0030 1 I(I4)
    0040 1 P(P7.2)
    0050 1 T(P7.2)
    0060 END-DEFINE
    0070 *
  
    0080 SETTIME
    0090 *
  
   000012 45E0 B040           BAL   R14,RETH   
   000016 0036                DC    X'0036'
  
    0100 FOR I=1 TO 100000

Example Section C:

000018 059B                BALR  R9,R11
   00001A 003E                DC    X'003E'
   00001C D203 7000 833B      MVC   I,#VAR033B
  
   000022 059B                BALR  R9,R11
   000024 004C                DC    X'004C'
   000026 47F0 A040           BC    15,64(,R10)
  
   00002A 059B                BALR  R9,R11
   00002C 005A                DC    X'005A'
   00002E BFFF 8343           ICM   R15,15,#VAR0343
   000032 BF0F 7000           ICM   R0,15,I
   000036 1A0F                AR    R0,R15
   000038 BE0F 7000           STCM  R0,15,I
  
   00003C 059B                BALR  R9,R11
   00003E 006C                DC    X'006C'
   000040 BFFF 833F           ICM   R15,15,#VAR033F
   000044 BF0F 7000           ICM   R0,15,I
   000048 190F                CR    R0,R15
   00004A 4720 A066           BC    2,102(,R10)
  
    0110   ADD 1.00 TO P
  
   00004E 059B                BALR  R9,R11
   000050 0082                DC    X'0082'
   000052 FA41 7004 8347      AP    P,#VAR0347
   000058 DC00 7008 B488      TR    P+4(1),PSGNTR
  
    0120 END-FOR
    0130 *
  
   00005E 059B                BALR  R9,R11
   000060 0094                DC    X'0094'
   000062 47F0 A02A           BC    15,42(,R10)
  
    0140 T:=*TIMD(0080)
  
   000066 059B                BALR  R9,R11
   000068 009C                DC    X'009C'
   00006A 45E0 B0D8           BAL   R14,SYSFUNC
   00006E 0330 B881           DC    X'0330B881'
  
   000072 F246 7009 8330      PACK  T,#VAR0330
   000078 F040 7009 0002      SRP   T,2,0
   00007E DC00 700D B488      TR    T+4(1),PSGNTR
  
    0150 T:=T / 10
    0160 *
  
   000084 059B                BALR  R9,R11
   000086 00AE                DC    X'00AE'
   000088 F864 D100 7009      ZAP   OP1(7),T
   00008E F811 D130 8349      ZAP   WORK2(2),#VAR0349
   000094 45E0 B104           BAL   R14,ZDCHECK
   000098 F240 7009 B355      PACK  T,ZEROZ
   00009E 47F0 E01C           BC    15,28(,R14)
   0000A2 FD61 D100 8349      DP    OP1(7),#VAR0349
   0000A8 D204 7009 D100      MVC   T,OP1
   0000AE DC00 700D B488      TR    T+4(1),PSGNTR
  
    0170 DISPLAY 'ELAPSED TIME (S)' T
  
   0000B4 45E0 B040           BAL   R14,RETH
   0000B8 00C0                DC    X'00C0'
  
    0180 END

Prerequisites for Code Generation with Unicode Operands

The Natural Optimizer Compiler generates optimized code for Natural statements with Unicode strings if the following requirements are met:

Statement Requirement
All statements All operands used in the statement must be of the type Unicode.
EXAMINE The ARCH option must be set to a value greater than or equal to 6.
IF

DECIDE FOR

DECIDE ON

  • All Unicode character strings must be normalized.

  • The ARCH option must be set to a value greater than or equal to 5.

  • The UNICC option must be set to ON or FORCE.

  • The COLLATE option of the CFICU profile parameter must be set to OFF (see the Parameter Reference documentation).

MOVE

MOVE SUBSTRING

RESET

The ARCH option must be set to a value greater than or equal to 5.

UNICC Option

The UNICC option controls the generation of optimized code for IF, DECIDE FOR and DECIDE ON statements that contain Unicode operands.

Valid values for UNICC are:

Value Explanation
ON Generates optimized code and checks whether COLLATE=OFF is set (see the CFICU profile parameter in the Parameter Reference documentation).

If COLLATE=ON is set, execution of the optimized code will fail with a NAT7023 Natural system error.

FORCE Generates optimized code analogous to ON but without COLLATE=OFF check.

The code optimized with FORCE performs better than the code optimized with ON but can cause wrong results if COLLATE=ON is set.

OFF Optimized code is not generated.

OFF is the default setting.

Influence of other Natural Parameters

The global parameter ZD influences the behavior of the NOC compiler. See the description of the ZD option as described under List of Options above.

The COMPOPT parameter PSIGNF (see also the system command COMPOPT in the Natural System Commands documentation) influences the behavior by forcing the signs of positive packed decimal numbers to F if ON, and to C if OFF. The parameter is applied if NOSGNTR=OFF is specified.

See the chart below for packed data (Format P) ":"

NOSGNTR=OFF and  PSIGNF=ON All signs are normalized to F (default).
NOSGNTR=OFF and  PSIGNF=OFF All signs are normalized to C.
NOSGNTR=ON   All signs are left as they were generated by the last operation.

For numeric data (Format N) the signs are always normalized to F, regardless of the settings of NOSGNTR and PSIGNF.