Group Control System: Difference between revisions

Revision as of 23:39, 13 February 2010

Revision as of 23:59, 13 February 2010

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{{orphan|date=December 2009}}

'''Group Control System''' ('''GCS''') is an [[operating system]] made by [[IBM]], meant to run as a guest of [[VM (operating system)|VM]]. guest operating systemGCS andis an integral component of the discontinued [[VM/SP]] (since VM/SP 4), VM/XA SP, [[VM/ESA]] and current [[z/VM]] IBM System product offerings.

ItsGCS's purpose is to provide an environment to run some specific [[MVS|OS/MVS]]-based applications and networking [[middleware]] under VM. To this end, GCS provides a limited simulation of the OS/MVS APIs. While [[Conversational Monitor System|CMS]], the usual VM guest, already has OS simulation, it is not extensive enough to run some applications such as [[VTAM]].

To this end, GCS provides a limited simulation of the OS/MVS APIs. While [[Conversational Monitor System|CMS]] already has OS simulation, it is not extensive enough to run some applications such as [[VTAM]] and VTAM applications.

Specifically, GCS provides OS multitasking support. In order to be able to spread the load over several virtual machines, GCS also implements a notion of group where each group member virtual machine can interact with one another.

To implement this, GCS uses several techniques:

* A writeable shared segment

* [[IUCV]] communications between virtual machines

* A recovery virtual machine -, designed to cleanup locks in the shared segments when virtual machines unexpectedly leave the group

GCS is not designed to be a multi-purpose user operating system (like CMS). For example, it does not allow for file editing.

GCS is not designed to be a multi-purpose user operating system (likesuch as CMS). For example, it does not allow for file editing.

Examples of programs designed to run under GCS are

Examples of programs designed to run under GCS are:

* VM/VTAM : The VM implementation of the VTAM stack

* [[RSCS]] : The Remote Spooling Communication Subsystem -, which, when associated with an instance of VM/VTAM, can use SNA resources to communicate with other SNA/NJE hosts

* [[NETVIEW]] : A networking monitoring service