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Compiling, Linking, and Executing Your Program When you compile your program, the COBOL compiler translates your COBOL source program to object code and resolves calls to nested programs. When you link your program, the link editor resolves calls to subprograms that are to be bound at link time (not all subprograms; see Chapter 4 ). Your program must be linked whether it calls such subprograms or not. The link editor uses object code to produce a program file. When you execute your program, the loader loads the program file into memory and the operating system executes it. Figure 6-1 shows how a source program becomes an executing program.Figure 6-1. How a Source Program Becomes an Executing Program If the source program consists of a main program and one or more subprograms, the main program and each subprogram must be compiled separately. The resulting object files must be linked together into a single program file. An object file cannot contain more than one program. Figure 6-2 shows the input to the COBOL compiler and the output from it.[REV BEG] Note that COPYLIB and INCLUDE files can also be used for input.[REV END] Formal file designators are in italic capital letters.Figure 6-2. COBOL Compiler Input and Output The rest of this section explains the following: * The two compiler entry points and the two compiler modes. * How to use file equations with the FILE command. * How to run the COBOL compiler with the MPE XL RUN command. * How to compile, link, and execute your program with Native Mode command files. * How to compile, link, and execute your program with Compatibility Mode compiler UDCs or commands. * How to use relocatable and executable libraries. * Examples of compiling, linking, and executing programs. Compiler Entry Points and Modes The COBOL compiler is "two compilers in one." That is, it has two entry points, ANSI74 and ANSI85. When you invoke it through the ANSI74 entry point, ANSI COBOL 1974 syntax and semantics apply. When you invoke it through the ANSI85 entry point, ANSI COBOL 1985 syntax and semantics apply. The ANSI74 entry point is provided for compatibility with older COBOL compilers. The COBOL compiler also has two modes, Native Mode and Compatibility Mode. In Native Mode, the compiler produces object code designed especially for the MPE XL operating system. This code runs very fast on MPE XL. In Compatibility Mode, the compiler produces object code designed especially for the MPE V operating system. It runs on MPE XL, but not as efficiently as Native Mode object code does, because MPE XL must simulate the MPE V system hardware and microcode. Compatibility Mode is provided for compatibility with the MPE V operating system. Both entry points are available in both modes. In summary, the entry points differ in the source code that they recognize, and the modes differ in the object code that they generate. Table 6-3 shows what the compiler does with each entry point in Native Mode and Compatibility Mode. Table 6-3. Entry Point and Mode Combination ------------------------------------------------------------------------------------------ | | | | | Entry Point | Native Mode | Compatibility Mode | | | | | ------------------------------------------------------------------------------------------ | | | | | ANSI85 | Translates ANSI COBOL 1985 source | Translates ANSI COBOL 1985 source | | | code to MPE XL object code. | code to MPE V object code. | | | | | ------------------------------------------------------------------------------------------ | | | | | ANSI74 | Translates ANSI COBOL 1974 source | Translates ANSI COBOL 1974 source | | | code to MPE XL object code. | code to MPE V object code. | | | | | ------------------------------------------------------------------------------------------ File Equations When you use a file equation (the FILE command), its formal designator must match the file name in the ASSIGN clause of the SELECT statement. Example. The following SELECT statement declares the logical file MY-FILE: SELECT MY-FILE ASSIGN TO "MFILE". The following file equation associates the logical file MY-FILE with the physical file REALFILE: :FILE MFILE=REALFILE You can use a file equation to do the following: * Tell your COBOL program to change the temporary file that it creates to a permanent file. For example, the following FILE command causes the temporary file MFILE to be made a permanent file: :FILE MFILE;SAVE One alternative to the FILE command is to use the SAVE command SAVE MFILE before the job or session ends. For example, the following also causes the temporary file MFILE to be made a permanent file: :SAVE MFILE * Override default file characteristics. * Create a circular file. * Create a message file. An alternative to a file equation or the FILE command in each of the above cases is to create the file with the BUILD command before you execute the program. For more information on files and the FILE command, see Chapter 5 . [REV BEG] Native Mode Compiler Command Files and RUN Command You can invoke the Native Mode COBOL compiler and compile your COBOL program in Native Mode with either the RUN command or one of the six command files COB85XL, COB85XLK, COB85XLG, COB74XL, COB74XLK, or COB74XLG. These command files can compile, link, and execute your program. You can use one of the six existing command files or write your own. For more information on compiling, linking, and executing your program, see the appendix "MPE XL System Dependencies" in the HP COBOL II/XL Reference Manual.[REV END] Compatibility Mode Compiler UDCs and Commands To compile your program in Compatibility Mode, use a UDC (User-Defined Command) or a command to compile, link, and execute your program. Table 6-4 and Table 6-5 list each UDC and command that invokes the Compatibility Mode COBOL compiler, the entry point through which it invokes the compiler, and its other effects. Table 6-4. Compatibility Mode UDCs -------------------------------------------------------------------------------------- | | | | | UDC | Entry Point | Invokes the compiler and: | | | | | -------------------------------------------------------------------------------------- | | | | | COBOLIIX | ANSI85 | Creates an object file. | | | | | -------------------------------------------------------------------------------------- | | | | | COBOLIIXPREP | | Links the object file and creates a program | | | | file. | | | | | -------------------------------------------------------------------------------------- | | | | | COBOLIIXGO | | Creates a program file in $OLDPASS and runs it. | | | | | -------------------------------------------------------------------------------------- Table 6-5. Compatibility Mode Commands -------------------------------------------------------------------------------------- | | | | | Command | Entry Point | Invokes the compiler and: | | | | | -------------------------------------------------------------------------------------- | | | | | COBOLII | ANSI74 | Creates an object file. | | | | | -------------------------------------------------------------------------------------- | | | | | COBOLIIPREP | | Links the object file and creates a program | | | | file. | | | | | -------------------------------------------------------------------------------------- | | | | | COBOLIIGO | | Creates a program file in $OLDPASS and runs it. | | | | | -------------------------------------------------------------------------------------- Syntax of UDCs. COBOLIIX [textfile][,[uslfile[,[listfile][,[masterfile] [,[newfile]]]]]][,info] COBOLIIXPREP [textfile][,[progfile[,[listfile][,[masterfile] [,[newfile]]]]]][,info] COBOLIIXGO [textfile][,[listfile][,[masterfile] [,[newfile]]]][,info] Syntax of Commands. COBOLII [textfile][,[uslfile[,[listfile][,[masterfile] [,[newfile]]]]]] [;INFO=info][;WKSP=workspacename] COBOLIIPREP [textfile][,[progfile[,[listfile][,[masterfile] [,[newfile]]]]]][;INFO=info][;WKSP=workspacename] COBOLIIGO [textfile][,[listfile][,[masterfile][,[newfile]]]] [;INFO=info][WKSP=workspacename] Parameters. textfile MPE or TSAM file containing your source program. This file can be compiled. The formal designator is COBTEXT. The default is $STDIN. uslfile Relocatable object code file. This file can be linked. The formal designator is COBUSL. The default is $OLDPASS. progfile Executable program file. This file can be executed. The default is $NEWPASS. listfile MPE file on which your source code will be listed. The formal designator is COBLIST. The default is $STDLIST. masterfile MPE or TSAM file to be merged with textfile to produce a composite source program. The formal designator is COBMAST. If masterfile is omitted, the entire source is from textfile. newfile MPE file into which the merged textfile and masterfile is written. For details, refer to the HP COBOL II/XL Reference Manual. The formal designator is COBNEW. The default is that no new file is written. info A string whose value is a command list of the form: "$compiler_command[$compiler_command]..." where no compiler_command contains the character $ (even if it is within quotes). Refer to the HP COBOL II/XL Reference Manual for more information on compiler commands. If the number of commands is long enough, you can use an ampersand (&) to continue the info string. The length limit for a compiler command is the same as the length limit for a source program line. In the listing file, the string "INFO=" appears where the sequence numbers normally appear. The info string is processed before any source, including compiler commands in the source. Therefore, you may not want to use the default settings of these commands in the source file. You should only include commands such as SUBPROGRAM, which are required for proper compilation, in the source file. This allows you to specify commands like NOLIST, MAP, BOUNDS, or CROSSREF uniquely within the info string for each compilation. workspacename Work space in which HP TOOLSET/XL can manage versions of the source program. Libraries Your program can use subprograms from relocatable libraries and executable libraries. Relocatable and executable libraries differ in content and in when they are referenced. The following table lists these differences: Table 6-6. Differences between Relocatable and Executable Libraries --------------------------------------------------------------------- | | | | | Library | Contents | Referenced At | | | | | --------------------------------------------------------------------- | | | | | Relocatable (RL) | Relocatable object | Link time. | | | modules. | | | | | | --------------------------------------------------------------------- | | | | | Executable (XL) | Executable object | Run time. | | | modules. | | | | | | --------------------------------------------------------------------- Relocatable Libraries. A relocatable library contains relocatable object modules and is referenced at link time. Example. The following shows how you can use the Link Editor to put the subprogram SUB1 into the relocatable library RLLIB. Your input is underlined: :LINKEDIT LinkEd>RL RLLIB LinkEd>ADDRL FROM=SUB1 LinkEd>EXIT The following command links subprograms from RLLIB with the object file of the main program, TMAIN, and creates the program file TMAINP: :LINK TMAIN,TMAINP;RL=RLLIB Executable Libraries. An executable library contains executable object modules and is referenced at run time. The three ways to tell the operating system which executable library contains the subprograms for your program are: 1. Specify the library in the LINK command. The advantage of this method is that you need not remember to specify the library in the RUN command each time you execute your program. The only time you cannot use this method is when you want to execute the program with different executable libraries at different times. The following command links subprograms from XLLIB.GROUP.ACCOUNT with the object file of the main program, TMAIN, and creates the program file TMAINP: :LINK TMAIN,TMAINP;XL=XLLIB.GROUP.ACCOUNT Either of the following commands runs the program: :RUN TMAINP This uses the RUN command. :TMAINP This uses the implied RUN command. 2. Specify the library in the RUN command. The advantage of this method is that you can execute the program with different executable libraries at different times. The following command executes the program TMAIN, in the program file TMAINP, with the executable library XLLIB.GROUP.ACCOUNT: :RUN TMAINP;XL="XLLIB.GROUP.ACCOUNT" 3. Name the library XL. In the RUN command, specify LIB=G if the library is in your group, LIB=P if the library is in your account, or LIB=S if the library is NL.PUB.SYS or XL.PUB.SYS. LIB=S is the default. This is the least flexible method. It is similar to the method used on the MPE V operating system. Examples of Compiling, Linking, and Executing Programs This section contains several examples of compiling, linking and executing programs. Example 1. The first example compiles, links, and executes a program. Either the program calls no subprograms, or the subprograms that it calls are in the executable library NL.PUB.SYS or XL.PUB.SYS. :COB85XL TPROG,,$NULL :LINK :RUN $OLDPASS The first command above compiles the COBOL source program, TPROG, into the default object file, $OLDPASS. $NULL specifies no listing. The second command links the default object file, $OLDPASS, into the default program file, $NEWPASS, which becomes $OLDPASS when it is closed. The third command executes the program file, $OLDPASS. The following single command is equivalent to the above sequence of three commands: :COB85XLG TPROG,$NULL Example 2. The second example compiles, links, and executes a main program and two subprograms. The main program and each subprogram is in a separate object file. The keyword RUN in the last command is optional. :COB85XL TMAIN,TMAINO :COB85XL SUB1,SUB1O :COB85XL SUB2,SUB2O :LINK FROM=TMAINO,SUB1O,SUB2O;TO=TMAINP :RUN TMAINP Example 3. The third example compiles, links, and runs concatenated programs. The first program is a main program. It uses an indirect file list of the programs to be compiled. When programs are concatenated, the compiler is invoked once for all of them, and the compiler output for these programs is in a single object file, so the FROM list in the LINK command only needs to specify one object file. The default $OLDPASS is used below. The "indirect" file, COBSRC, contains: $INCLUDE MAINSRC END PROGRAM MAINSRC. $INCLUDE SUB1SRC END PROGRAM SUB1SRC. $INCLUDE SUB2SRC END PROGRAM SUB2SRC. $INCLUDE SUB3SRC The END PROGRAM header is not necessary for the last concatenated program in a file. This is an easy way to migrate your current main and subprograms to concatenated programs, and simplify your compiles and links. The following commands compile and link the file COBSRC: :COB85XL COBSRC :LINK :$OLDPASS The defaults for the object file and program file are used above. The RUN keyword is not necessary to run the program file, $OLDPASS.
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