Converting SCS and 3270 data streams to line data streams

In each printer definition, you can select a NetSpool formatting option. The formatting option controls how NetSpool formats the data streams created by your VTAM® applications. You can select one of these formatting options:

• Convert to line (default)
• Convert to PCL
• None

This section describes the Convert to line formatting option. When you select the Convert to line option, NetSpool converts SCS data streams (on VTAM LU type 1 sessions) and 3270 data streams (on VTAM LU type 0 and type 3 sessions) to line data streams.

You can select the Convert to line option for a wide range of printers, including:

• Line printers controlled by JES

  Line printers that natively accept line data streams.

• AFP printers controlled by PSF

  AFP printers do not natively accept line data streams. However, PSF can convert line data streams to Intelligent Printer Data Streams (IPDS), which AFP printers accept.

• Network printers controlled by IP PrintWay™

  Network printers do not natively accept line data streams. However, IP PrintWay can convert line data streams to ASCII text data streams, which most network printers accept. If you install the separately priced AFP to PCL, AFP to PDF, or AFP to PostScript transform, NetSpool can convert line data streams to PCL, PDF, or PostScript data streams.

  Tip:

  The NetSpool Convert to PCL formatting option is also suitable for most network printers. When NetSpool converts input data streams to PCL data streams, it can support more of the formatting options in the original data streams, such as print density and line density, than when it converts to line data streams.

When you select the Convert to line option, NetSpool converts the printable data, SCS controls, and 3270 controls in the input data stream to line data with ANSI carriage-control characters. Carriage-control characters control line spacing and skipping operations. NetSpool supports most of the SCS and 3270 controls in the input data stream that are associated with printing. However, NetSpool ignores those SCS and 3270 controls for which no equivalent support exists in line data. NetSpool writes the line data to the JES spool in variable-length, blocked records, with a maximum record size of 4092 bytes.

To fill in the fields in the printer definition that are related to NetSpool formatting, you should understand these functions that NetSpool provides when you select the Convert to line option:

• Page formatting: NetSpool formats data into lines and pages before writing it to the JES spool. The page formatting is different for SCS and 3270 input data streams.

  SCS data streams: NetSpool uses the SCS Set Horizontal Format (SHF) and SCS Set Vertical Format (SVF) controls in the input data stream to format data into lines and pages. The SHF and SVF controls specify page-formatting values such as line length, page length, margins, and tabs. The SHF and SVF controls take effect immediately and remain in effect until either the next SHF or SVF control or until NetSpool establishes another VTAM session with the printer.

  If the SCS data stream does not contain SHF and SVF controls, NetSpool uses default values. In each printer definition, you can specify the default values that NetSpool is to use for the line length, page length, margins, and tabs.

  3270 data streams: NetSpool uses the 3270 Write Control Characters (WCCs) in the input data stream to format data into lines and pages. To change page-formatting values for 3270 data, the application programmer must change the WCCs generated by the VTAM application that creates the 3270 data. NetSpool does not use the SCS default page-formatting values specified in the printer definition when it formats 3270 data.

• DBCS support: NetSpool supports these SCS and 3270 controls and orders, which identify double-byte character set (DBCS) strings:
  • Shift Out and Shift In
  • Set Attribute, with the Character Set attribute
  In addition, NetSpool supports these 3270 orders, which identify DBCS strings:
  • Start Field Extended with the Character Set attribute
  • Modify Field with the Character Set attribute
  In place of these controls and orders, NetSpool inserts Shift Out and Shift In line-data controls where necessary in the line-data output. When you print DBCS data on printers controlled by PSF, you must select the PSF SOSI2 option to prevent printing unwanted blanks.

For tables that describe how NetSpool converts SCS and 3270 data streams to line data streams, see z/OS Infoprint Server Customization.