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Browse Prior Art Database

Coresident Preferred Systems Via Relocate

IP.com Disclosure Number: IPCOM000079806D
Original Publication Date: 1973-Sep-01
Included in the Prior Art Database: 2005-Feb-26
Document File: 3 page(s) / 46K

Publishing Venue

IBM

Related People

Larson, LE: AUTHOR

Abstract

Described is a change to an existing operating system (OS/VS1) to permit coresidency of another control program subject to the following constraints: 1) The host system (OS/VS1) has a dependency upon low-storage address, and has relocate support existing. 2) The host system uses 2-byte address constants in certain control blocks, which are a) in the first part of a control section called IOS (input/output subsystem), and b) required to map via relocate directly to a real-storage address. 3) The change to the host system must be insignificant. The number of components effected must be small. 4) The second control program likewise has 2-byte address constants. 5) The second control program has a response time requirement which prohibits the translation of its channel programs.

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Coresident Preferred Systems Via Relocate

Described is a change to an existing operating system (OS/VS1) to permit coresidency of another control program subject to the following constraints:
1) The host system (OS/VS1) has a dependency upon low-storage

address,

and has relocate support existing.
2) The host system uses 2-byte address constants in certain

control

blocks, which are a) in the first part of a control section

called

IOS (input/output subsystem), and b) required to map via

relocate directly to a real-storage address.
3) The change to the host system must be insignificant. The

number

of components effected must be small.
4) The second control program likewise has 2-byte address

constants.
5) The second control program has a response time requirement

which

prohibits the translation of its channel programs.
6) The overhead of channel translation by OS/VS1 and then a

second

translation by the second control program is unacceptable.

Fig. 1 presents the Low Address virtual equal real area of the existing operating system (OS/VS1). Fig. 2 presents the modified existing operating system which has a Filler CSECT (Control Section) added, and a MONITOR partition added. Fig. 3 presents the low-address area, and the mapping function of relocate used to achieve the desired end.

The processing required to move the system environment from Fig. 1 to 2 to 3 is as follows:
1. The host system is rebuilt with a CSECT filler added to

accommodate

the size of the second control program. The system is then

IPL'ed

(Initial...