C PLIST and EXECOPS interactions

You can use C #pragma runopts to specify to the C compiler a list of options to be used at run time. Two of the options of #pragma runopts affect the format of the argument list passed to the application on initialization: EXECOPS and PLIST.

EXECOPS allows you to specify runtime options on the command line or in JCL at application invocation. NOEXECOPS indicates that runtime options cannot be so specified. When the EXECOPS runtime option is specified under MVS™, Language Environment alters the MVS parameter list format: Language Environment removes any runtime options that are present.

PLIST indicates in what form the invoked routine should expect the argument list. You can specify PLIST with the following values under Language Environment:

HOST

The argument list is assumed to be a character string. The string is located differently under various systems as follows:

Under TSO, if a CPPL is detected, Language Environment gets the string from the command buffer.
Under TSO, if a CPPL is not detected, Language Environment assumes a halfword-prefixed string in the MVS format.
Under MVS, Language Environment uses the halfword-prefixed string.

OS

The inbound parameter list is assumed to be in an MVS linkage format in which register 1 points to a parameter address list. No runtime options are available. Register 1 is not interrogated by Language Environment.

The PLIST(HOST) setting allows the object to execute under MVS (assuming a halfword-prefixed string), or under TSO (using the CPPL or the MVS-format parameter list). Specify PLIST(HOST) to default to the argument list format for the operating system under which your application is running.

Although Language Environment supports the MVS, IMS™, and TSO suboptions of PLIST for compatibility, use of PLIST(HOST) is recommended. There are some exceptions to this guideline:

Preinitialization: PLIST(MVS) is supported for compatibility with pre-Language Environment C preinitialization programs.
CICS®: If you are running a CICS application compiled under the pre-Language Environment-conforming version of C, PLIST(HOST), the default, is assumed regardless of the actual PLIST setting. If you are running a CICS application compiled with a Language Environment-conforming C compiler, specify PLIST(OS).
TSO: TSO command processors that require access to the full CPPL must specify PLIST(OS).

The EXECOPS, NOEXECOPS, and PLIST options can alter the format of the argument list passed to your application, depending on the combination of options specified. The setting of EXECOPS determines whether Language Environment looks for runtime parameters in the inbound parameter list. The effects of the interactions of these options under the various operating systems and subsystems are summarized in Table 1:

Table 1. Interactions of C PLIST and EXECOPS
Operating system	Method of invocation	PLIST suboption	EXCECOPS (default)	arg/argv	__R1/__osplist and PCBs
MVS	EXEC PGM=, PARM= <runtime options> / <user args>	HOST	Yes. <runtime options> honored	argc = number of tokenized args in <user args> argv[0…argc-1] = tokenized args in <user args>
MVS	EXEC PGM=, PARM= <runtime options> / <user args>	HOST	No. <runtime options> ignored	argc = number of tokenized args in the entire PARM string, that is, <runtime options> / <user args> argv[0…argc-1] = tokenized args in the entire PARM string
MVS	Assembler calls C module with pre-Language Environment preinitialization PLIST with runtime options specified in the PLIST	MVS	Yes. <runtime options> honored	argc/argv = <argc,argv> structure specified in the preinitialization PLIST
MVS	Assembler calls C module with pre-Language Environment preinitialization PLIST with runtime options specified in the PLIST	MVS	No. <runtime options> ignored	argc/argv = <argc,argv> structure specified in the preinitialization PLIST
MVS	Driver link to C main passing noncharacter parameter list	OS	n/a	argc=1 argv[0] = name of C main program module	Access register 1 through __osplist macro as defined in stdlib.h
TSO	CALL, LOADGO, execute module on TSO command line passing <runtime options> / <user args>	HOST	Yes. <runtime options> honored	argc = number of tokenized args in <user args> argv[0…argc-1] = tokenized args in <user args>
TSO	CALL, LOADGO, execute module on TSO command line passing <runtime options> / <user args>	HOST	No. <runtime options> ignored	argc = number of tokenized args in <runtime options> / <user args> argv[0…argc-1] = tokenized args in <user args>
TSO	CALL	OS	n/a	argc=1 argv[0] = name of module	Access CPPL through __osplist as defined in stdlib.h
IMS	Invoke C main module	OS or IMS Specify ENV(IMS) also.	n/a	argc=1 argv[0] = name of C main module or null if the #pragma runopts(PLIST(IMS)) is present in the source	Access PCBs through C macros as defined in ims.h
CICS	Invoke C main module	n/a	n/a	argc=1 argv[0] = transaction id