On Friday, 03/30/2007 at 10:54 ZE2, Shimon Lebowitz <[EMAIL PROTECTED]> wrote: > > > > I tested this years ago when we encountered problems with messages that > > seemed to get lost > > > But is it documented? > Things from 'years ago' sometimes change with no > announcement when they are undocumented internals. > > I am not arguing with you, I myself have no vague idea, > just wondering if this old 'feature' is guaranteed to still > be true.
>From Ch. 16 (*MSG) of the CP Programming Services book: "The Message system service uses the IUCV default value of 255 for the number of outstanding messages allowed on the path unless the user specifies a value for the MSGLIM parameter. If a value is specified on the IUCV CONNECT for MSGLIM to *MSG, that value is used for the number of messages allowed on the path. If this message limit is exceeded, any additional incoming messages are routed directly to the virtual machine console or alternate console, and the virtual machine is not notified about these messages." But because WAKEUP reads the message in immediately and queues it in CMS, even when you're not in WAKEUP at the moment, the CP message limit only comes into play when (a) Your virtual machine is disabled for external interrupts (b) The rate of message arrival is faster than the virtual machine running WAKEUP can read & queue them I remember some of the original attempts at IBMers writing *MSG handlers. They only did the IUCV RECEIVE when you issued their "get next message" command. People who used those programs were often victimized by the MSGLIM. Alan Altmark z/VM Development IBM Endicott
