IBM manual Subsystem Level Comparison/Affinity, What Changes Between VSE and OS/390?, Security

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:

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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.

24VSE to OS/390 Migration Workbook