must also be X'02'. When using BALR, the calling program can determine the
entry point it wants by using SUBCOM. In this case, register 1 points to the FSCB
and register 2 points to the SCBLOCK. The address of the the SCBLOCK has
been returned from SUB COM. The routines available, their entry point names, and error return codes are:
DMSXFLST -This routine returns the characteristics of a file (RECFM,
LRECL, etc). It also ensures that the file is in the XED IT ring. The return
codes are:
o File is in the XED IT ring
24 Incomplete fileid specified
28 File is not in the XEDIT ring
Note: Return codes are similar to those for ESTATE.
DMSXFLRD -This routine transfers one record from XEDIT storage to the
calling program. If RECFlVI=F, it may transfer more than one record. The
return codes are:
o READ performed
1 File is not in the XEDIT ring
2 Invalid buffer address
5 Number of items equals zero
7 RECFM is not 'F' or 'V' 8 Buffer is too small (Records truncated)
11 Number of items is not equal to one for V-file
12 End of file
Note: Return codes are similar to those for FSREAD.
DMSXFL WR -This routine transfers one record from the calling program to
XEDIT storage. If RECFM=F, it may transfer more than one record. The
return codes are:
o WRITE performed
2 User buffer address equals zero
7 Skip over unwritten records
8 Number of bytes is not specified
11 RECFM is not 'F' or 'V' 13 No more space is available
14 Number of bytes is not integrally divisible by the number of item
15 Item length is not the same as previous
16 RECFM of 'F' or 'V' is not the same as previous
18 Number of items is not equal to one for V-file
28 File is not in the XEDIT ring
Note: Return codes are similar to those for FSWRITE. DMSXFLPT - This routine moves the current line pointer to a record specified
by the calling program. The return codes are:
o POINT performed
1 File not found
2 Invalid FSCB
Functional Infonnation 349

Note: Return codes are similar to those for FSPOINT. When the interface is used, XED IT determines if a file is in the XEDIT ring (active
in storage) and does the processing required. The files in the XED IT ring are
always open. New files may be added to the ring with the XEDIT subcommand.
Files in the ring may be closed with the FILE or QUIT subcommands.
The current line pointer serves the function of both the read and write pointers of
the CMS file system. If RECNO=O is specified in a call to DMSXFLRD, then the
data will be transferred to the calling program starting at the current line pointer.
Transfer is stopped when the specified number of lines has been transferred or
when end-of-file is reached. The current line pointer is advanced by one for each
record transferred to the calling program. If the current line pointer was at the
end-of-file when DMSXFLRD was called, no data is transferred and an end-of-file
condition is returned.
If RECNO=O is specified in a call to DMSXFLWR, the new records are written
starting at the line pointed to by the current line pointer, replacing any existing
records, or adding new records if at the end-of-file. The current line pointer is
advanced to the line following the last line written at the end of the operation.
Note that writing to a record in the middle of a V-format file does not result in
truncation of the file from that point, as it would in the CMS file system.
eMS Interface for Display Terminals
CMS has an interface that allows it to display large amounts of data in a very rapid
fashion. This interface for 3270 display terminals (also 3138, 3148, and 3158) is
much faster and has less overhead than the normal write because it displays up to 1760 characters in one operation, instead of issuing 22 individual writes of 80 characters each (that is one write per line on a display terminal). Data that is dis­
played in the screen output area with this interface is not placed in the console
spool file.
The DISPW macro allows you to use this display terminal interface. It generates a
calling sequence for the CMS display terminal interface module, DMSGIO. DMSGIO creates a channel program and issues a DIAGNOSE instruction (Code
X'58') to display the data. DMSGIO is a TEXT file which must be loaded in order
to use DISPW. The format of the CMS DISPW macro is:
[label]
where:
label
bufad 350 VM/SP System Programmer's Guide DISPW bufad [ 'LINE=n] [ ,BYTES=bbbbJ ,LINE=O ,BYTES=1760
[ERASE=YES] [CANCEL=YES]
is an optional macro statement label.
is the address of a buffer containing the data to be written to the dis­
play terminal.