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in your environment. Each should be researched individually for installation
applicability.
2.2.2 Subsystem Level Comparison/Affinity
Various sections in this publication deal with the VSE and OS/390 subsystems
and detail their similarities and differences. Specifically, these subsystems are:
•
DB2/VSE and DB2/MVS
•
DL/I and IMS/DB
•
CICS/VSE and CICS/ESA
•
POWER and JES
•
Telecommunications (VTAM, NCP, BTAM)
•
ICCF and TSO
Refer to these sections for specific details of subsystem level comparison/affinity
and migration issues.
2.3 What Changes Between VSE and OS/390?
The particular items discussed in this section may have some significant impact
as you enter the OS/390 environment. How it is decided to implement the
changes in these key areas will effect the amount of effort and resources that
will be required for the migration and subsequent production environment.
2.3.1 Philosophical Changes
One of the most signification philosophical changes when going from VSE to
OS/390 is that of the design points of the two operating systems. OS/390 has at
its design point a strong focus on systems management, specifically systems
availability. Thousands of lines of operating system code is dedicated to
preventing and/or reducing IPLs, system and program ABENDs and unscheduled
downtime. This may mean a big change for those VSE environments where
frequently scheduled IPLs are a regular occurrence.
2.3.1.1 Security
Customers who have developed security policies and procedures within the VSE
environment will find developing similar policies and procedures under OS/390
fairly straightforward. However, as with many of the products providing
equivalent VSE function in the OS/390 environment actual product
implementation may be different. This applies also to the security product
chosen for OS/390. OS/390 focuses on system integrity, that is, security checking
is done prior to performing any function.
Customers who have chosen to implement little or no security with VSE may find
themselves doing so with OS/390. If this is the case then policies and procedures
will have to be developed and a security package, for example RACF, chosen to
implement these policies and procedures.
24 VSE to OS/390 Migration Workbook