PDPCLIB.HELPCMD.D1

 
PDPCLIB - An implemention of the C90 Library for GCC
 
    PDPCLIB is an implemntation of the C90 runtime library. It has been
    implemented on several platforms and the CMS port is based on the
    MVS code with minor adaptations to allow it to work in CMS.
 
    The C90 standard is over 30 years old and so the library does NOT
    contain many of the routines a modern programmer expects. Specifically
    it includes the routines described in the following header files:-
 
    <assert.h>
    <ctype.h>
    <errno.h>
    <float.h>
    <limits.h>
    <locale.h>
    <math.h>
    <setjmp.h>
    <signal.h>
    <stdarg.h>
    <stddef.h>
    <stdio.h>
    <stdlib.h>
    <string.h>
    <time.h>
 
    If your "C" program uses a system include that is not in that list, its not
    part of PDPCLIB and you may have to port it yourself.
 
    Using PDPCLIB
    =============
 
    The GCC EXEC that runs the GCC compiler and the CMS Assembler
    uses PDPCLIB by default. The necessary ".h" files
    are stored on the GCCCMS 201 disk and the EXEC will link and access
    this disk by default.
 
    The PDPCLIB TXTLIB Y contains the object modules necessary to load
    "C" programs that use this library. It must be specified in a
    "GLOBAL TXTLIB" command before loading a "C" program.
 
    As PDPCLIB uses OS QSAM emulation to read and write files, a
    "FILEDEF" command is needed for each file that is open. To ease
    the burden on "C" programmers and to simpify porting code from
    other platforms, the PDPCLIB open routines will issue a FILEDEF
    command to create a Dataset Descriptor (DD) for it to use.
 
    The DD names used are of the form "PDP<00000>" and these may
    appear in error messages. If you wish to issue your own FIELDEF
    commands use a filename of the form:
 
     "DD:<ddname>"
 
    and PDPCLIB will not issue a FILEDEF, but expect a DD of <ddname>
    to exist. This allows non-disk files such as tapes and printers
    to be accessed.
 
    IO Redirection
    ==============
 
    The PDPCLIB startup routine uses the following DD names for
    the standard "C" streams.
 
    C Stream Name       DD name
     stdin              SYSIN
     stdout             SYSTERM
     stderr             SYSPRINT
 
     If there are no existing FILEDEFS for these streams the startup routine
     will issue FILEDEFs to assign them to the VM Console.
 
     If they are defined it will attempt to use them which permits standard
     IO to be re-directed in a clunky way.
 
     PARM File
     =========
 
     When PDPCLIB was first ported to CMS there was an issue with passing
     the command line to the program. As released VM/CMS splits the command
     line into tokens, truncating each token to 8 chacaters. This makes
     running tradional "C" programs challenging. In order to allow a full
     un-edited command line to be passed the PARMFILE mechanism was concocted.
     When the C startup code runs it checks to see if a DD of PARMFILE is
     allocated. If it is, it will read the command line from the file and
     pass it to main() in argv[].
 
     Its not usually necessary to use this as CMS has been modified to
     allow access to a full command line, this mechanism remains in place
     to permit EXECs that use it to continue to work.