Hi Ram ,
The number of the records that you can see in main window on a page depends on the main window size . Now , you want to utilize the maximum possible space . Lets us assume that 19 records can fit in you main window depending on you main window size .
Do one thing . Create a variable counter . Assign 1 to COUNTER initally .
IF &counter& mod 19 = '0' .
/: NEW-PAGE .
ENDIF .
&counter& = &counter& + 1 .