execshv

Guidelines for Subcommand Processing

Under CMS, programs receive an "*ENDEXEC" string indicating that an EXEC invoked externally has completed, and the program has been reentered during CMS end-of-command processing via the L$CEXEC nucleus extension (see the execinit description earlier in this chapter). Noninteractive execution of SUBCOM applications cannot be supported in bimodal CMS because, by the time the the library's end-of-command nucleus extension is entered, CMS has already purged program modules from memory. Under the USS shell, the SAS/C REXX interface runs as a separate process from the calling program to prevent interference between the program and EXEC processing. Since the REXX interface is in a separate process, it is possible that the interface could be terminated by a signal at any time. When this occurs, on the next call to a SUBCOM function, errno is set to EINTR . Because the REXX interface has been terminated, the program cannot thereafter use any SUBCOM functions other than execend . Once execend has been called, it is possible to call execinit to create a new SUBCOM environment.

Chapter Contents
Previous
Next
Top of Page