A number of CMS6 and CMS7 sites have reported "hung conditions" whereby
LISTSERV keeps processing reader files and answers console commands, but
appears to ignore all commands sent via TELL. Eventually you get a
'LISTSERV not receiving; IUCV error 001' message and LISTSERV has to be
re-IPL'ed to solve the problem.
The problem seems to be due to the SET SERVER command introduced in CMS6.
With the default setting, CMS is liable to disable IUCV interrupts under
undocumented and at best obscure conditions; the use of SFS would seem to
make it more likely to happen. SET SERVER ON appears to have the side
effect of not making CMS turn off IUCV interrupts in this fashion. So
far, the problem could not be reproduced with SET SERVER ON. The next
release of LISTSERV will issue this command at startup, but CMS6/7/8
sites should include it in PROFILE EXEC for the time being.
Eric