keep-together.within-page EXCEPT if it is to big ?

Hello, 

We are using 
keep-together.within-page="always"
to implement a block of framed text, because we don't want the frame to be split over 2 pages - except if the frame is bigger than a page. Is there a way to implement the 'except' part?
Here's the solution that works nicely as long as the framed text is smaller than the page size:

<xsl:template match="framed">
    <fo:block margin-bottom="15px"
              margin-top="13px"
              margin-left="15px"
              margin-right="15px"
              keep-together.within-page="always">
        <xsl:apply-templates select="node()"/>
    </fo:block>
</xsl:template>

The problem is that if the content of the framed element is bigger than the page size, the overflow is lost. 

Thanks,
Werner