code:

---

cls
break on

$rc=setoption('NoVarsInStrings','on')
$rc=setoption('Explicit','on')

dim $StartStringLength, $FinalStringLength, $StringSegmentLength, $StringSegmentsToAdd
dim $SegmentCount, $CurrentStringLength, $CurrentSize, $StringSegment

$StartStringLength=0
$FinalStringLength=25000000000
$StringSegmentLength=10000000

$StringSegmentsToAdd=cdbl($FinalStringLength)/$StringSegmentLength

dim $StringSegmentPart[$StringSegmentLength/1000], $String[cdbl($StartStringLength)/$StringSegmentLength]
$StringSegmentPart=join($StringSegmentPart,'abcdefghij')
$StringSegment=''
for $SegmentCount=1 to 100
  $StringSegment=$StringSegment+$StringSegmentPart
next
$SegmentCount = 0

if ubound($StartStringLength)
  $String=join($String,'abcdefghij')
endif
;$rc=redirectoutput(@SCRIPTDIR+'\stringtest.txt')

? 'String Length Start   = ' + formatnumber(len($String),0,-1)
? 'String Length Final   = ' + formatnumber($FinalStringLength,0,-1)
? 'String Segment Length = ' + formatnumber(len($StringSegment),0,-1)
? '# Segments To Add     = ' + formatnumber($StringSegmentsToAdd,0,-1)

while $SegmentCount<$StringSegmentsToAdd and not @ERROR
  $String=$String+$StringSegment
  $SegmentCount=$SegmentCount+1
  $CurrentStringLength=cdbl(len($String))
  $CurrentSize=val($CurrentStringLength/1024/1024)
  ? 'Current String Length ('+formatnumber($SegmentCount,0,-1)+') = ' + formatnumber($CurrentStringLength,0,-1) + ' = ' +formatnumber($CurrentSize,0,-1) +' MB'
loop
if not @ERROR
  ? 'Final String Length ('+formatnumber($SegmentCount,0,-1)+') = ' + formatnumber($CurrentStringLength,0,-1) + ' = ' +formatnumber($CurrentSize,0,-1) +' MB'
else
  ? 'Error at step '+$SegmentCount+' = ' + formatnumber(len($String),0,-1)+ ' = '+formatnumber(cdbl(len($String))/1024/1024,0,-1)+' MB'
endif

exit 0

---