Performance Considerations

For each AFP printer, the manufacturer specifies the maximum number of pages (or impressions) per minute that the printer is capable of printing. Use this number as a "model" when investigating how many pages per minute are actually printed. The variety of printing characteristics and the complexity of the output has a significant influence on printer performance. In many cases, the printer’s speed is significantly less than its maximum rated speed.

When using Control-D, there are a number of guidelines that may help in improving AFP printer performance. Not all AFP users experience problems with printer performance, but those users who do should read this section.

In-Line Resources

Control-D in-line resources can improve PSF performance. The performance improvement depends on the variety of PAGEDEFs and FORMDEFs that are used by your data center’s output. PSF holds in its memory up to seven copies of the most previously used PAGEDEFs and up to seven copies of the most recently used FORMDEFs. PAGEDEFs and FORMDEFs are used only by PSF and are not loaded to the printer. PAGEDEFs and FORMDEFs are instructions to PSF on how to format the output. PSF formats the output and sends it to the printer formatted, using IPDS (Intelligent Printer Data Stream). IPDS is the data stream that is used by PSF to communicate with the printer. It is a two way communication. Fonts, overlays and Page Segments (images) are downloaded to the printer. The more resident fonts, the better the performance. Page Segments can be included in an output by an overlay or by specifying an IPS structured field. When using the IPS structured field, you can optionally specify the Page Segment in the Page Segment list of the PAGEDEF. This is the suggested method for performance reasons, but it is not a requirement.

Using the Control-D in-line resource option, printer performance may be improved when using more than seven PAGEDEFs or seven FORMDEFs. This is because Control-D relieves PSF from reading the PAGEDEFs and the FORMDEFs from an external library at the time when the output is already selected to print from spool. Control-D reads the PAGEDEFs and the FORMDEFs from the external libraries in advance, immediately before sending the output to spool.

Using a Global PAGEDEF and FORMDEF

In data centers that use a relatively small variety of PAGEDEFs and FORMDEFs, one global PAGEDEF and one global FORMDEF are defined. The general idea is to define all original PAGEDEFs in one global PAGEDEF, each as Page Formats in the global PAGEDEF. The same can be done for a global FORMDEF. Define all original FORMDEFs in one global FORMDEF, each as Copy Groups in the global FORMDEF. The main advantage of this method is improved printer performance.

The APAPARM option must be used for correct selection of the required Page Format and/or Copy Group. For a detailed description of this option, refer to The APAPARM Option.

The specific Page Format and Copy Group to be used for each report are specified in the APAPARM library. The Page Format and Copy Group names appear in the PAGEDEF and FORMDEF. If the name is not known, it can easily be displayed by browsing the PAGEDEF or FORMDEF member in the system or user PAGEDEF/FORMDEF library. For PAGEDEFs, the line that displays the Page Format name (in Hex) is the BDM command X‘D3A8CA’ (Begin Data Map). For FORMDEFs, the line that displays the Copy Group name (in Hex) is the BMM command X‘D3A8CC’ (Begin Medium Map). The name itself appears in regular text format on the same line.

IBM supplied PAGEDEFs usually contain a Page Format with the same (or close to the same) name as the PAGEDEF, as do IBM supplied FORMDEFs and Copy Groups. User-defined PAGEDEFs and FORMDEFs usually use the same standard as IBM. For user-defined PAGEDEFs where the original PAGEDEF has more than one Page Format, or for user-defined FORMDEFs where the original FORMDEF has more than one Copy Group, use a logical name for the Page Format/Copy Group. For example, if the original PAGEDEF was named P1STATEM, then you could name the Page Formats as follows: STATEM1, STATEM2, and so on.

Resident Fonts

With printers that support resident fonts, try to have as many commonly used fonts resident on the printer as possible. This can dramatically improve printer performance. Fonts can be loaded as resident fonts on various AFP printers using the PSF APSRMARK utility. For a detailed description of the APSRMARK utility, refer to the PSF System Programmers Guide.

Four-Font Data Centers

When using up to four fonts, consider using the following:

CHARS=(chars1,chars2,chars3,chars4)

Each output is specified with the font used as the first font in the list of four fonts. This way all four most commonly used fonts are always loaded on the printer, improving performance.

Small Reports and Small Chunks

When printing many small reports using a large variety of PAGEDEFs, FORMDEFs, Fonts, Page Segments and Overlays, do not expect the same printer speed as when printing a large report with a small variety of printing characteristics. Take advantage of the sorting options in the Control-D printing missions. For example, sort by CHARS (fonts) when applicable. This can speed up printing in many situations.

Page Segments

When using the IPS structured field to include a Page Segment, it is best to specify the Page Segment in the Page Segment list of the active PAGEDEF. This improves performance during printing.

Special 3800 Considerations

The 3800 AFP Laser Printer has almost the same technical capabilities as other AFP printers. It is important, however, to be aware of certain differences that can be very significant to some data centers.

The most significant difference is the size of the printer storage. The size of the printer storage determines how many external resources can be stored in the printer at a given time and the capability of the printer to print complex output. The standard printer storage for the 3800 Model 3 printer is up to 512 K. You can purchase a special feature called "3800 Storage Expansion Feature" to expand the storage. Using this feature, the printer storage can reach 4 MB. There is an additional feature called "3800 Accumulator" that can also improve printer performance. Although it is possible to expand the printer storage, most data centers that have the 3800 Model 3 do not have these features.

Therefore, when printing AFP output using the 3800 Laser Printer, try and keep the output simple (not complex) and use a smaller variety of external resources.

Remote Print Manager (RPM)

Remote Print Manager (RPM) stores all fonts, Overlays and Page Segments on a PS/2 that is connected directly to the remote channel attached printer. This means that the transmitting of output to an RPM printer includes almost only the data. This is extremely good for performance. This, in conjunction with in-line PAGEDEFs and FORMDEFs on the mainframe for PSF, provides the best combination for remote printing. Not all AFP printers are supported by RPM. See the relevant IBM publications for additional information about RPM and which AFP printers are supported.

PSF/2 replaces RPM. For information about PSF/2, see PC/LAN Environment.