test: field norms.........ERROR [Java heap space] on Luke

test: field norms.........ERROR [Java heap space] on Luke

I am not an experience user of Luke and I need to run some diagnostics on
my current index. I have clicked on "Check Index" and I am returned with
the following results:
Segments file=segments_lda numSegments=1 version=3.6.1 format=
1 of 1: name=_2gnd docCount=6475520
codec=Lucene3x
compound=false
numFiles=8
size (MB)=17,132.164
diagnostics = {mergeFactor=32, os.version=2.6.18-308.24.1.el5,
os=Linux, lucene.version=3.6.1 1362471 - thetaphi - 2012-07-17
12:36:25, source=merge, os.arch=amd64, mergeMaxNumSegments=1,
java.version=1.6.0_41, java.vendor=Sun Microsystems Inc.}
has deletions [delGen=-1]
test: open reader.........OK
test: fields..............OK [52 fields]
test: field norms.........ERROR [Java heap space]
I do not know what to make of test: field norms.........ERROR [Java heap
space] What does it really mean? What does it tell me of my index?
Thanks!