328 IBM System ?rogrammer's Guide

Introduction to RSCS The Remote Spooling Communications Subsystem (RSCSj, a component of VM/370, provides telecommunication facilities for the transmission of
bulk files between VM/370 users and remote stations. RSCS is a single
purpose operating system for a virtual machine, dedicated to the
management of files spooled to it by VM/370 users or transmitted to it
by remote stations via communication lines. Remote stations can submit
files to a VM/370 user or CMS Batch Facility for processing and receive
printer and punch output in return,. VM/370 users can submit job streams
to a remote HASP- or ASP-type batch processor. Remote stations can send
printer and punch files to other remote stations.
Locations and Links Under RSCS, all remote locations as well as the local RSCS virtual
machine are assigned a one-to eight-character alphameric location
identification. The transmission path between the RSCS virtual machine
and any single remote station is defined as a link. A link has certain
attributes that make up a link definition and these attributes are
assigned at system generation time or dynamically via the RSCS DEFINE
command. A link definition consists of a linkid (the location
identifier of the remote station), the type of remote station, the line
address to be used for transmission, the class of files to be processed,
and other information unique to the link. RSCS maintains a table of link
definitions (link table) in the module DMTSYS. A maximum of 64 links may
be defined of which any 16 may be active at anyone time.
Remote Stations
A remote station, in the context of RSCS, is any terminal or system on the other end of the link from the RSCS virtual machine. The RSCS virtual machine is also referred to as the local RSCS station. RSCS supports two general types of I/O configurations used as remote
stations.
Nonprogrammable remote terminals, such as the IBM 2780, are I/O configurations where the line protocol necessary for them to function as
remote stations is provided by the hardware. These devices are managed
by the Nonprogrammable Terminal (NPT) line driver of RSCS. Programmable remote stations, such as the IBM System/3 and System/360, are IBM processing systems with attached binary synchronous
communications adapters. These systems must be programmed to provide a MULTI-LEAVING line protocol necessary for their devices to function as
remote stations. For a detailed description of see
"Appendix B: MULTI-LEAVING." This programming support is provided by a
Remote Terminal Processor (RTP) program generated according to HASP workstation protocol and tailored to the system's hardware
configuration. Certain programmable remote stations like the System/3
can only be programmed to function as remote terminals. Others, like the System/360 and System/370, can function either as remote terminals or as
host batch systems using RSCS as a remote job entry workstation. Both
of these types of remote stations are managed by the Spool MULTI-LEAVING (SML) line driver of RSCS. Part 4. Remote Spooling Communications Subsystem (RSCS) 329