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APAR status

  • Closed as canceled.

Error description

    II02481. Following subject should be also documented,but II02481
    was full, so we have to open a new one. This InfoAPAR contains
    information to JES/328X with title:"HOW JES/328x PROCESSES FCBs"

Local fix

  • ********************************************
    The following description covers the key points necessary to
    understand how JES/328x handles FCB processing.  It contains
    information that will assist customers in understanding why some
    FCBs that have worked for many years with channel-attached
    devices do not work in a remote printer environment using
    The original IBM mainframe printer, the 1403, used a paper tape
    to control the positioning of the form.  The data stream used to
    communicate with this channel-attached device was simple, either
    120 or 132 bytes in length.  This data stream is still used
    The "form" in this environment was a repeatable unit in a
    continuous stationary stream, eg the standard 66 line page.
    The paper tape was loaded as a continuous, repeating loop and
    different codes on the paper tape were used to control the
    movement of the paper stationary.  The different codes in the
    paper tape were called "channels".  The printer's microcode knew
    how to position the paper stationary based on the contents of
    the paper tape.
    In this environment it was valid to have multiple occurences of,
    say, channel 1, defined on the tape.  The convention was that
    channel 1 was "the first printable line on the page" and channel
    12 was the "last printable line on the page".  Form feeds were
    achieved by having a Channel 1 at the appropriate position.
    Channels were used/needed to save the overhead of the printer
    performing a line feed to every line on the page.  With a
    properly defined paper tape a "skip to channel x" would advance
    the paper several lines at once.
    It was possible to use a paper tape that was 66 lines long when
    printing, for example, cheques that occupied half (33 lines), or
    a third (22 lines) of a standard page.  To do this, the same
    channel was repeated on the tape at the appropriate interval (ie
    33 or 22 lines apart in this example).
    Later printers did away with the paper tape, but used the more
    familiar Forms Control Buffer (FCB) to provide the same
    function.  (See the DFSMS Advanced Services and DFSMS Utilities
    manuals for more information).  The FCB image was downloaded
    from the host into the printer as required.
    Note that this is for channel-attached printers, the processing
    for remotely attached printers is different.
    JES2 imposes a restriction that Channel 1 must be in position 1
    for all JES2 controlled printers (see above).  The documentation
    for printers like the 3289 includes detailed instructions on how
    to construct an FCB for a particular form.  While not
    specifically disallowing an FCB with the same channel defined
    multiple times, the instructions make it clear that a properly
    defined FCB will have:
    o  the form length defined as the smallest repeatable unit of
       printed output.  For continuous stationary this is normally
       the distance between perforations, however it could be less
       than this;
    o  the line count equal to the number of lines on the form;
    o  channel 1 defined at the top of the form;
    o  channel 12 defined at the bottom of the form.
    In other words, a form that is half a normal page in length
    should be defined as 33 lines in length, rather than 66 lines in
    Length with 2 lines (33 lines apart) defined as channel 1.
    The 3211 printer added an "indexing feature".  This is
    essentially a horizontal tab to set the left margin of the form.
    FCBs for the 3211 printer have an indicator byte at position 3,
    plus an extra byte immediately thereafter to indicate the
    horizontal offset.  Printers that do not support the indexing
    feature generally ignore the extra byte.
    To repeat the point above, because it is important:  FCB images
    are downloaded into channel attached printers.  The processing
    for remote printers is different.
    JES/328x never sends the FCB it receives from JES to the target
    printer.  This is true even for printers capable of being
    channel attached and which are defined to JES/328x as LUTYPE=0.
    Note that SETUP=PDIR must be specified for the FCB and UCS
    information to be passed from JES to JES/328x.  The JES/328x
    device driver is always defined to JES as an LUTYPE=1 device, so
    the communications protocol between JES and JES/328x is always
    SNA.  JES/328x also communicates with the target printer using
    the SCS (SNA Character Stream) protocol, wherever possible.  In
    those cases where SCS processing is not applicable (ie LUTYPE=0
    or LUTYPE=3), JES/328x emulates the SNA character stream.
    JES/328x converts "skips to channels" to the appropriate number
    of new-line characters.
    The two relevant SCS commands are:
    SVF (Set Vertical Format) and;
    VCS (Vertical Channel Select)
    Consult the relevant SNA manual(s) for detailed information.
    When using the SVF command to set the channels for a form, there
    is no provision to define channel 1 other than as "top of form".
    Similarly, channels 2 to 12 must be defined in ascending order,
    and each channel can therefore only be defined (at most) once.
    The result of these SNA protocol restrictions is that some FCBs
    that worked for channel-attached printers will not work in a
    remote printer environment.
    In summary then, there are various restrictions that must be
    observed for JES/328x to correctly process an FCB.  These
    restrictions arise from limitations in the SCS commands used by
    JES and JES/328x to communicate in a remote-printer, as opposed
    to a channel-attached environment.  The restrictions are:
    o  SETUP=PDIR must be specified
    o  The form length must be defined correctly
    o  Channel 1 must be defined at position 1
    o  If Channel 12 is used, it should be defined as the bottom
       of the form
    o  No channel can be defined more than once.
    o  The indexing byte can be specified, but is ignored by
    The JES/328x Program Description and Operations Manual,
    SB11-8776-02 will be updated with the following change (when
    next revised):
    On page 7, "Restrictions", add the following to item 5:
    "JES/328x does not support FCBs where the same channel is
    defined more than once."
    The Preventative Service Planning (PSP) document for JES/328x -
    Upgrade ID = JES/328x, Subset ID = HBY3202 has been updated with
    this and other documentation changes.

Problem summary

Problem conclusion

Temporary fix


  • Closed 21/7/2000

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Fix information

Applicable component levels

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Document Information

Modified date:
21 July 2000