StackOverflow problem when using FOP in multi threaded environment

while executing a simple pdf generation from a servlet context, there is a problem of Stack oveflow, but if i do call the same transformation commands (the same as FOP site examples, but using saxon fo having xslt2 features) a standalone application it doesn't crash:

Starting Helma in directory /home/kraken/REPOSITORY
Starting HTTP server on port 8090
Starting AJP13 listener on port 8009
Adding to classpath: /home/kraken/REPOSITORY/lib/ext/saxon9sa.jar
Adding to classpath: /home/kraken/REPOSITORY/lib/ext/xmlgraphics-commons.jar
Adding to classpath: /home/kraken/REPOSITORY/lib/ext/fop.jar
Adding to classpath: /home/kraken/REPOSITORY/lib/ext/avalon-framework.jar
Starting Helma 1.6.2 (September 23 2008) on Java 1.5.0_13
[2008/09/23 11:12:28] [INFO] Starting Helma 1.6.2 (September 23 2008) on Java 1.5.0_13
[2008/09/23 11:12:28] [INFO] Setting Helma Home to /home/kororaa/REPOSITORY
[2008/09/23 11:12:28] [INFO] Starting AJP13-Listener on port 0.0.0.0:8009
[2008/09/23 11:12:28] [INFO] Version Jetty/5.1.14
...
[2008/09/23 12:03:11] [DEBUG] Dynamically adding maker for Renderer: org.apache.fop.render.pdf.PDFRendererMaker
[2008/09/23 12:03:11] [DEBUG] Dynamically adding maker for Renderer: org.apache.fop.render.ps.PSRendererMaker
[2008/09/23 12:03:11] [DEBUG] Dynamically adding maker for Renderer: org.apache.fop.render.txt.TXTRendererMaker
[2008/09/23 12:03:11] [DEBUG] Dynamically adding maker for Renderer: org.apache.fop.render.bitmap.PNGRendererMaker
[2008/09/23 12:03:11] [DEBUG] Dynamically adding maker for Renderer: org.apache.fop.render.bitmap.TIFFRendererMaker
[2008/09/23 12:03:11] [DEBUG] Dynamically adding maker for Renderer: org.apache.fop.render.xml.XMLRendererMaker
[2008/09/23 12:03:11] [DEBUG] Dynamically adding maker for Renderer: org.apache.fop.render.awt.AWTRendererMaker
[2008/09/23 12:03:11] [DEBUG] Dynamically adding maker for Renderer: org.apache.fop.render.print.PrintRendererMaker
[2008/09/23 12:03:11] [DEBUG] Dynamically adding maker for Renderer: org.apache.fop.render.afp.AFPRendererMaker
[2008/09/23 12:03:11] [DEBUG] Dynamically adding maker for Renderer: org.apache.fop.render.pcl.PCLRendererMaker
[2008/09/23 12:03:11] [DEBUG] Dynamically adding maker for FOEventHandler: org.apache.fop.render.rtf.RTFFOEventHandlerMaker
[2008/09/23 12:03:11] [DEBUG] target-resolution set to: 72.0dpi (px2mm=0.35277778)
[2008/09/23 12:03:11] [DEBUG] Dynamically adding PDFImageHandler: org.apache.fop.render.pdf.PDFImageHandlerRawJPEG
[2008/09/23 12:03:11] [DEBUG] Dynamically adding PDFImageHandler: org.apache.fop.render.pdf.PDFImageHandlerRawCCITTFax
[2008/09/23 12:03:11] [DEBUG] Dynamically adding PDFImageHandler: org.apache.fop.render.pdf.PDFImageHandlerGraphics2D
[2008/09/23 12:03:11] [DEBUG] Dynamically adding PDFImageHandler: org.apache.fop.render.pdf.PDFImageHandlerRenderedImage
[2008/09/23 12:03:11] [DEBUG] Dynamically adding PDFImageHandler: org.apache.fop.render.pdf.PDFImageHandlerXML
[2008/09/23 12:03:11] [DEBUG] userconfig is null
[2008/09/23 12:03:11] [DEBUG] Registering: any,normal,400 under F5
[2008/09/23 12:03:11] [DEBUG] Registering: any,italic,400 under F6
[2008/09/23 12:03:11] [DEBUG] Registering: any,oblique,400 under F6
[2008/09/23 12:03:11] [DEBUG] Registering: any,normal,700 under F7
[2008/09/23 12:03:11] [DEBUG] Registering: any,italic,700 under F8
[2008/09/23 12:03:11] [DEBUG] Registering: any,oblique,700 under F8
[2008/09/23 12:03:11] [DEBUG] Registering: sans-serif,normal,400 under F1
[2008/09/23 12:03:11] [DEBUG] Registering: sans-serif,oblique,400 under F2
[2008/09/23 12:03:11] [DEBUG] Registering: sans-serif,italic,400 under F2
[2008/09/23 12:03:11] [DEBUG] Registering: sans-serif,normal,700 under F3
[2008/09/23 12:03:11] [DEBUG] Registering: sans-serif,oblique,700 under F4
[2008/09/23 12:03:11] [DEBUG] Registering: sans-serif,italic,700 under F4
[2008/09/23 12:03:11] [DEBUG] Registering: SansSerif,normal,400 under F1
[2008/09/23 12:03:11] [DEBUG] Registering: SansSerif,oblique,400 under F2
[2008/09/23 12:03:11] [DEBUG] Registering: SansSerif,italic,400 under F2
[2008/09/23 12:03:11] [DEBUG] Registering: SansSerif,normal,700 under F3
[2008/09/23 12:03:11] [DEBUG] Registering: SansSerif,oblique,700 under F4
[2008/09/23 12:03:11] [DEBUG] Registering: SansSerif,italic,700 under F4
[2008/09/23 12:03:11] [DEBUG] Registering: serif,normal,400 under F5
[2008/09/23 12:03:11] [DEBUG] Registering: serif,oblique,400 under F6
[2008/09/23 12:03:11] [DEBUG] Registering: serif,italic,400 under F6
[2008/09/23 12:03:11] [DEBUG] Registering: serif,normal,700 under F7
[2008/09/23 12:03:11] [DEBUG] Registering: serif,oblique,700 under F8
[2008/09/23 12:03:11] [DEBUG] Registering: serif,italic,700 under F8
[2008/09/23 12:03:11] [DEBUG] Registering: monospace,normal,400 under F9
[2008/09/23 12:03:11] [DEBUG] Registering: monospace,oblique,400 under F10
[2008/09/23 12:03:11] [DEBUG] Registering: monospace,italic,400 under F10
[2008/09/23 12:03:11] [DEBUG] Registering: monospace,normal,700 under F11
[2008/09/23 12:03:11] [DEBUG] Registering: monospace,oblique,700 under F12
[2008/09/23 12:03:11] [DEBUG] Registering: monospace,italic,700 under F12
[2008/09/23 12:03:11] [DEBUG] Registering: Monospaced,normal,400 under F9
[2008/09/23 12:03:11] [DEBUG] Registering: Monospaced,oblique,400 under F10
[2008/09/23 12:03:11] [DEBUG] Registering: Monospaced,italic,400 under F10
[2008/09/23 12:03:11] [DEBUG] Registering: Monospaced,normal,700 under F11
[2008/09/23 12:03:11] [DEBUG] Registering: Monospaced,oblique,700 under F12
[2008/09/23 12:03:11] [DEBUG] Registering: Monospaced,italic,700 under F12
[2008/09/23 12:03:11] [DEBUG] Registering: Helvetica,normal,400 under F1
[2008/09/23 12:03:11] [DEBUG] Registering: Helvetica,oblique,400 under F2
[2008/09/23 12:03:11] [DEBUG] Registering: Helvetica,italic,400 under F2
[2008/09/23 12:03:11] [DEBUG] Registering: Helvetica,normal,700 under F3
[2008/09/23 12:03:11] [DEBUG] Registering: Helvetica,oblique,700 under F4
[2008/09/23 12:03:11] [DEBUG] Registering: Helvetica,italic,700 under F4
[2008/09/23 12:03:11] [DEBUG] Registering: Times,normal,400 under F5
[2008/09/23 12:03:11] [DEBUG] Registering: Times,oblique,400 under F6
[2008/09/23 12:03:11] [DEBUG] Registering: Times,italic,400 under F6
[2008/09/23 12:03:11] [DEBUG] Registering: Times,normal,700 under F7
[2008/09/23 12:03:11] [DEBUG] Registering: Times,oblique,700 under F8
[2008/09/23 12:03:11] [DEBUG] Registering: Times,italic,700 under F8
[2008/09/23 12:03:11] [DEBUG] Registering: Courier,normal,400 under F9
[2008/09/23 12:03:11] [DEBUG] Registering: Courier,oblique,400 under F10
[2008/09/23 12:03:11] [DEBUG] Registering: Courier,italic,400 under F10
[2008/09/23 12:03:11] [DEBUG] Registering: Courier,normal,700 under F11
[2008/09/23 12:03:11] [DEBUG] Registering: Courier,oblique,700 under F12
[2008/09/23 12:03:11] [DEBUG] Registering: Courier,italic,700 under F12
[2008/09/23 12:03:11] [DEBUG] Registering: Symbol,normal,400 under F13
[2008/09/23 12:03:11] [DEBUG] Registering: ZapfDingbats,normal,400 under F14
[2008/09/23 12:03:11] [DEBUG] Registering: Times-Roman,normal,400 under F5
[2008/09/23 12:03:11] [DEBUG] Registering: Times-Roman,oblique,400 under F6
[2008/09/23 12:03:11] [DEBUG] Registering: Times-Roman,italic,400 under F6
[2008/09/23 12:03:11] [DEBUG] Registering: Times-Roman,normal,700 under F7
[2008/09/23 12:03:11] [DEBUG] Registering: Times-Roman,oblique,700 under F8
[2008/09/23 12:03:11] [DEBUG] Registering: Times-Roman,italic,700 under F8
[2008/09/23 12:03:11] [DEBUG] Registering: Times Roman,normal,400 under F5
[2008/09/23 12:03:11] [DEBUG] Registering: Times Roman,oblique,400 under F6
[2008/09/23 12:03:11] [DEBUG] Registering: Times Roman,italic,400 under F6
[2008/09/23 12:03:11] [DEBUG] Registering: Times Roman,normal,700 under F7
[2008/09/23 12:03:11] [DEBUG] Registering: Times Roman,oblique,700 under F8
[2008/09/23 12:03:11] [DEBUG] Registering: Times Roman,italic,700 under F8
[2008/09/23 12:03:11] [DEBUG] Registering: Computer-Modern-Typewriter,normal,400 under F9
[2008/09/23 12:03:11] [DEBUG] Building formatting object tree
[2008/09/23 12:03:11] [DEBUG] Current heap size: 7229KB
[2008/09/23 12:03:11] [DEBUG] Starting layout
[2008/09/23 12:03:11] [DEBUG] [1]
[2008/09/23 12:03:11] [DEBUG] PLM> flow BPD =792870
[2008/09/23 12:03:11] [DEBUG] start of the next element list is: page=1 col=0
[2008/09/23 12:03:11] [ERROR] null: java.lang.StackOverflowError
java.lang.StackOverflowError
at java.lang.ThreadLocal.get(ThreadLocal.java:125)
at sun.misc.FloatingDecimal.developLongDigits(FloatingDecimal.java:312)
at sun.misc.FloatingDecimal.dtoa(FloatingDecimal.java:549)
at sun.misc.FloatingDecimal.(FloatingDecimal.java:442)
at java.lang.StringBuffer.append(StringBuffer.java:365)
at org.apache.fop.fo.properties.PercentLength.toString(PercentLength.java:121)
at java.lang.String.valueOf(String.java:2615)
at java.lang.StringBuffer.append(StringBuffer.java:220)
at org.apache.fop.fo.flow.table.TableColumn.toString(TableColumn.java:233)
at java.lang.String.valueOf(String.java:2615)
at java.lang.StringBuffer.append(StringBuffer.java:220)
at org.apache.fop.datatypes.LengthBase.toString(LengthBase.java:135)
at java.lang.String.valueOf(String.java:2615)
at java.lang.StringBuffer.append(StringBuffer.java:220)
at org.apache.fop.fo.properties.PercentLength.toString(PercentLength.java:121)
at java.lang.String.valueOf(String.java:2615)
at java.lang.StringBuffer.append(StringBuffer.java:220)
at org.apache.fop.fo.flow.table.TableColumn.toString(TableColumn.java:233)
at java.lang.String.valueOf(String.java:2615)
at java.lang.StringBuffer.append(StringBuffer.java:220)
at org.apache.fop.datatypes.LengthBase.toString(LengthBase.java:135)
at java.lang.String.valueOf(String.java:2615)
at java.lang.StringBuffer.append(StringBuffer.java:220)
at org.apache.fop.fo.properties.PercentLength.toString(PercentLength.java:121)
at java.lang.String.valueOf(String.java:2615)
at java.lang.StringBuffer.append(StringBuffer.java:220)
at org.apache.fop.fo.flow.table.TableColumn.toString(TableColumn.java:233)
at java.lang.String.valueOf(String.java:2615)
at java.lang.StringBuffer.append(StringBuffer.java:220)
at org.apache.fop.datatypes.LengthBase.toString(LengthBase.java:135)
at java.lang.String.valueOf(String.java:2615)
at java.lang.StringBuffer.append(StringBuffer.java:220)
at org.apache.fop.fo.properties.PercentLength.toString(PercentLength.java:121)
at java.lang.String.valueOf(String.java:2615)
at java.lang.StringBuffer.append(StringBuffer.java:220)
at org.apache.fop.fo.flow.table.TableColumn.toString(TableColumn.java:233)
at java.lang.String.valueOf(String.java:2615)
at java.lang.StringBuffer.append(StringBuffer.java:220)
at org.apache.fop.datatypes.LengthBase.toString(LengthBase.java:135)
at java.lang.String.valueOf(String.java:2615)
at java.lang.StringBuffer.append(StringBuffer.java:220)
at org.apache.fop.fo.properties.PercentLength.toString(PercentLength.java:121)
at java.lang.String.valueOf(String.java:2615)
...

It seems a problem in the FOP library, or maybe a clash of some java classe in path.