IBM OS/390 User Manual
without disruption. Sessions are simply taken over by a new copy of the
application running in the same, or a different, processor.
application running in the same, or a different, processor.
9.1.2.1 Resource Definition
The OS/390 VTAM resource definitions are stored in the VTAMLST data set. Most
of the VSE/VTAM resource definitions (B-books), typically stored in the
PRD2.CONFIG VSE library, can be moved directly into the VTAMLST data set
without modification. There are several items worth noting here:
of the VSE/VTAM resource definitions (B-books), typically stored in the
PRD2.CONFIG VSE library, can be moved directly into the VTAMLST data set
without modification. There are several items worth noting here:
•
If migrating from VSE/VTAM V3R4 or older, MVS and VSE will differ in their
use of VTAM buffers. VSE/VTAM V3R4 utilizes the LFBUF pool for I/O and two
unique fixed size buffer pools (VFBUF and VPBUF) for pool expansions.
VFBUF defines storage for expansion of fixed storage buffer pools and
VPBUF for expansion of pageable storage buffer pools. VSE/VTAM V4R2
storage pools and usage was designed to be similar to MVS/VTAM. VFBUF
and VPBUF buffer pools were eliminated and the IOBUF buffer pool was
added for I/O. IOBUF size should be matched to NCP (UNITSZ) buffer size
and tuned for your requirements. All the other OS/390 buffer pool definitions
have reasonable defaults and can usually be left alone until it is time for fine
tuning.
use of VTAM buffers. VSE/VTAM V3R4 utilizes the LFBUF pool for I/O and two
unique fixed size buffer pools (VFBUF and VPBUF) for pool expansions.
VFBUF defines storage for expansion of fixed storage buffer pools and
VPBUF for expansion of pageable storage buffer pools. VSE/VTAM V4R2
storage pools and usage was designed to be similar to MVS/VTAM. VFBUF
and VPBUF buffer pools were eliminated and the IOBUF buffer pool was
added for I/O. IOBUF size should be matched to NCP (UNITSZ) buffer size
and tuned for your requirements. All the other OS/390 buffer pool definitions
have reasonable defaults and can usually be left alone until it is time for fine
tuning.
•
If you are converting a Token-Ring ICA attachment to a 3172 or OSA
attachment, you will need to replace your Local Area Network (LAN) major
node with an External Communication Adapter (XCA) major node to define
the connection.
attachment, you will need to replace your Local Area Network (LAN) major
node with an External Communication Adapter (XCA) major node to define
the connection.
•
Where the VTAM definitions refer to a data set, the coding often changes.
This mainly occurs in NCP definitions; please refer to 9.2, “ACF/NCP” on
page 192 for details.
This mainly occurs in NCP definitions; please refer to 9.2, “ACF/NCP” on
page 192 for details.
9.1.2.2 Operation
Most of the OS/390 VTAM console commands will be familiar to the VSE
operator. One point of interest is that the DISPLAY, VARY and HALT commands
are VTAM commands so that they take the format D NET..., V NET... and so on.
On the other hand, START and MODIFY are OS/390 commands so they must
refer to the actual name of the VTAM start procedure. Thus if VTAM is started
using
operator. One point of interest is that the DISPLAY, VARY and HALT commands
are VTAM commands so that they take the format D NET..., V NET... and so on.
On the other hand, START and MODIFY are OS/390 commands so they must
refer to the actual name of the VTAM start procedure. Thus if VTAM is started
using
S NET28,,,(LIST=S0)
then a subsequent MODIFY command will appear so
(for example)
F NET28,TRACE,...
.
9.1.3 Customization and Programming
VTAM tuning can be quite different under VSE and OS/390. Matters such as
optimizing I/O across a channel and pacing the flow of traffic are very similar,
but OS/390 VTAM uses storage and buffer pools in a completely different fashion
than VSE, so this aspect of tuning needs to be reviewed in some detail. Please
see the chapter
optimizing I/O across a channel and pacing the flow of traffic are very similar,
but OS/390 VTAM uses storage and buffer pools in a completely different fashion
than VSE, so this aspect of tuning needs to be reviewed in some detail. Please
see the chapter
Tuning VTAM for Your Environment in the Network
Implementation Guide for advice on tuning OS/390 VTAM.
9.1.3.1 VTAM Tables
Most of the VTAM tables which are assembled and linked do not differ between
OS/390 and VSE, but the use of mode tables needs to be considered.
OS/390 and VSE, but the use of mode tables needs to be considered.
VSE provides a VTAM mode table called IESINCLM. It is a subset of the default
VTAM mode table (ISTINCLM) but also contains some unique entries. IESINCLM
is routinely used in VSE systems, but is not provided by OS/390 VTAM. Migration
of the table and/or unique entries may be required. Refer to the
VTAM mode table (ISTINCLM) but also contains some unique entries. IESINCLM
is routinely used in VSE systems, but is not provided by OS/390 VTAM. Migration
of the table and/or unique entries may be required. Refer to the
VSE/ESA
Networking Support manual for more information on IESINCLM.
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VSE to OS/390 Migration Workbook