PM74893: CLARIFY USAGE OF SYSIN AS STDIN VIA THE TERMINAL/CONSOLE

Obtain the fix for this APAR.

APAR status

• Closed as program error.

Error description

• Documentation in the Enterprise PL/I Programming Guide is
  unclear with regards to I/O behavior when SYSIN is set to STDIN
  and coming from the terminal/console.
  

Local fix

Problem summary

• ****************************************************************
  * USERS AFFECTED: Enterprise PL/I users who use record I/O     *
  *                 (READ) to read SYSIN via STDIN from the      *
  *                 terminal.                                    *
  *                                                              *
  ****************************************************************
  * PROBLEM DESCRIPTION: Documentation in the PL/I manuals is    *
  *                      unclear when it comes to reading SYSIN  *
  *                      from STDIN via the terminal under the   *
  *                      USS environment.                        *
  *                                                              *
  ****************************************************************
  * RECOMMENDATION: Apply the PTF for this APAR.                 *
  *                                                              *
  ****************************************************************
  Available documentation is not clear regarding the use of record
  I/O to read SYSIN input coming from the terminal under the USS
  environment. It is stated in the manual that stream I/O is the
  recommended method for accessing data via the terminal, but it
  does not say that record I/O can not be used.
  
  Items to be addressed by this APAR:
  
  1. The latter part of the following statement is confusing and
  does not seem to apply to how PL/I currently works. This can be
  found in the Programming Guide, under the section "Redirecting
  standard input, output, and error devices under z/OS UNIX":
  
       READ statements can access data from stdin; however, the
       record into which the data is to be put must have an LRECL
       of 1.
  
  2. It is unclear how to signal end-of-file for input coming from
  the terminal.
  
  3. From testing various scenarios, two record I/O problems
  (using the READ statement) were discovered when input comes
  from the terminal.
  
     3a. When running under z/OS UNIX foreground, the /* sequence
     was not recognized as an end-of-file marker.
  
     3b. When running under BPXBATCH, reading from SYSIN via
     STDIN loops in the ENDFILE on-unit for the file. Including a
     GOTO statement in the on-unit circumvented the problem.
  

Problem conclusion

• The following documentation changes will be made to the
  Enterprise PL/I for z/OS Version 4 Release 3 Programming Guide,
  GI11-9145-02, to provide more information in regards to the use
  of STDIN:
  
  1. Under the chapter "Using data sets and files"
      section "Establishing data set characteristics"
      section "Specifying characteristics in the
                 ENVIRONMENT attribute"
      section "Redirecting standard input, ouput, and
                 error devices under z/OS UNIX"
  
      Modify the statement to read as follows:
        READ statements can also access data from stdin.
  
  2. Under the chapter "Defining and using consecutive data sets"
      section "End-of-file"
  
      Replace the section text with the following:
  
        The characters / in position one and * in position two
        of a line that contains no other characters are treated
        as an end-of-file marker; that is, they raise the
        ENDFILE condition.
  
        Under the USS environment, the key sequence ESC-D can
        also be used to indicate the end-of-file marker.
        The ESC key is predefined as a specific character,
        and it is this predefined character that needs to be
        used in the sequence.
  
  3a. Code has been modified in the PL/I run-time library to
  recognize the slash-asterisk sequence as an end-of-file marker
  for record I/O programs running under USS foreground with the
  SYSIN input coming from the terminal.
  
  3b. Code has been modified in the PL/I run-time library to fix
  the loop that occurred in the ENDFILE on-unit when a program
  reads from SYSIN and is run under BPXBATCH.
  

Temporary fix

Comments

APAR Information

• APAR is sysrouted FROM one or more of the following:

• APAR is sysrouted TO one or more of the following:

  UK91451 UK91453 UK91452

Modules/Macros

•    IBMPRCAA
  

Publications Referenced

GI11914502

Fix information

• Fixed component name

  LE VA PL/I

• Fixed component ID

  568819806

Applicable component levels

• R760 PSY UK91451

     UP13/02/08 P F302

• R770 PSY UK91452

     UP13/02/08 P F302

• R780 PSY UK91453

     UP13/02/08 P F302

Fix is available

• Select the PTF appropriate for your component level. You will be required to sign in. Distribution on physical media is not available in all countries.