Page Overflow Basics

Learning Objective

By the end of this lesson, you will understand what page overflow is, and how an RPGLE program uses an overflow indicator to reprint a heading on each new page.

Simple Explanation

The Report Headings and Detail Lines lesson printed one heading followed by many detail lines, without considering what happens once those detail lines fill an entire printed page. Page overflow is what IBM i calls reaching the bottom of the current page; a printer file can be set up with an overflow indicator that automatically turns on once the page is nearly full.

dcl-f CUSTRPTP printer;
dcl-f CUSTMAST disk;

write HDGFMT;

read CUSTMAST;
dow not %eof(CUSTMAST);
  if *inof;
    write HDGFMT;
  endif;

  write DTLFMT;

  read CUSTMAST;
enddo;

Here, *inof is the overflow indicator, tied to the printer file's DDS so that IBM i turns it on automatically once the current page fills up. Checking if *inof; inside the loop, before writing each detail line, lets the program reprint HDGFMT at the top of the new page whenever overflow occurs, so every page of the report has its own heading rather than only the very first one.

Why It Matters

Without handling page overflow, a multi-page report's later pages would have no heading at all, just an unbroken run of detail lines, making a long report much harder to read. Checking the overflow indicator and reprinting the heading is what keeps every page of a report properly labeled.

Practical Example

Imagine the daily customer balance report running against a CUSTMAST containing hundreds of customers, far more than fit on a single printed page. As the detail lines fill the first page, IBM i turns on the overflow indicator once the page is nearly full. The next time through the loop, the program notices *inof is on, prints HDGFMT again at the top of a fresh page, and continues printing detail lines from there.

This is a simplified, illustrative example rather than a specific real report, but it reflects exactly how a long report stays readable across many pages.

Common Confusions

"Does the program need to count lines itself to know when a page is full?" No. The overflow indicator is turned on automatically by IBM i, based on how the printer file's DDS is set up, without the RPGLE program needing to count printed lines itself.

"What happens if the overflow check is left out entirely?" The report would still print correctly in terms of its data, but later pages would be missing their heading, making a long, multi-page report significantly harder to read and navigate.

*"Is inof a special indicator only usable for this one purpose?" Within the scope of this lesson, *inof specifically represents the overflow condition tied to a printer file. Detailed configuration of exactly how and where overflow is set up in a printer file's DDS is a more advanced topic beyond this introduction.

Quick Recap

• Page overflow is IBM i's term for reaching the bottom of the current printed page.
• An overflow indicator, such as *inof, turns on automatically once a page is nearly full.
• Checking the overflow indicator before writing each detail line lets a program reprint the heading at the top of every new page.
• Without handling overflow, a multi-page report's later pages would have no heading at all.

Try Asking the AI Tutor

Use the AI Tutor to ask follow-up questions about this lesson. For example, try asking:

• "Does the overflow indicator turn itself back off after the heading is reprinted?"
• "Could a report have different behavior on overflow besides just reprinting the same heading?"