MSIR.0439 User pushdown list overflowed
This message is issued if the Sirius Mods "accurate PDL High Water Mark" calculation found that the user push down list exceeded the LPDLST parameter value, even though the usual Model 204 checking of the user push down list did not find excess. The accurate PDL HWM calculation is done if the SIRPDLHW parameter is 1.
See the documentation for message M204.1329.