IBM System/370 Guide

Page of GC20-1730-0
Revised 11/20/70
By TNL GN20-2277
reorganization, and all processing programs that access the BDAM data
set, is necessary if a relative track or actual address reference is
used and fewer (or more) 3330 tracks are allocated to the data set
than before.
Subject to the restrictions stated in Section 10:05 and those
indicated for BDAM data sets, existing executable processing programs
can be used without change to process data sets that have been
transferred to 3336 packs. Nothing need be done to job control for
these programs if the cataloged procedures supplied with the language
translators are used, as long as the 3330 facility is specified as
a SYSDA device at system generation. Otherwise, job control statements
must be changed to request 3330 devices and, optionally, any data set
characteristic changes" such as block size,. RPS support, as described
previously, is provided automatically.
User-written programs that use the EXCP level to access disk data
sets that have been transferred to 3336 packs may have to be modified
to reflect the characteristics of the data set on the 3336: a different
number of records per track, a different number of tracks per cylinder,
etc. All 2311 and 2314 CCW lists will operate on 3330 facilities
except those that are device or channel time dependent and those that
use the file scan commands, which are not available on the 3330. User-
written 2311 or 2314 error routines will not execute correctly and
must be modified. RPS commands have to be added by the user if this
support is desired for programs that use EXCP. (Note that the XDAP
macro will include support of RPS commands.)
Data sets currently located on 2301 Drum storage can be placed on
2305 modules by means of a data set utility program. Unit specification
in the job control statements of existing programs that will access
the 2305 module instead of the 2301 drum must be changed. Also, to
reflect the smaller capacity of a 2305 track, it may be necessary to
alter the block size used. The latter can also be done via job control
statement alterations (without program reassembly) unless block size
was specified in the program itself or record length is larger than
2305 track size.
CONVERSION TO THE 3803/3420 MAGNETIC TAPE SUBSYSTEM
As stated in Section 20:25, existing tape processing programs
and their job control statements and tape volumes need not be
modified in order to be used with 3803/3420 subsystems with equi-
valent features whenever the same recording modes are used.
Whenever possible, seven- and nine-track NRZI mode tape volumes
should be converted to 1600-BPI PE format to obtain the benefits of
the higher density and the PE recording technique. In cases in
which tape volumes must retain seven-track NRZI format, for inter-
change with other systems for example, use of the 3803/3420 sub-
system offers improved tape reliability and subsystem serviceability
as already discussed.
Conversion of seven- and nine-track NRZI tape volumes can be done
gradually during production processing. That is, the old master
input tape volume is read in on a 3420 tape unit with the appropri-
ate compatibility (Dual Density or Seven-Track) feature while the
new master output tape is written on 'a 3420 tape unit in 1600-BPI
PE format. Existing programs that process these converted tapes
need not be modified unless an altered characteristic (recording
mode or block size, for example) is specified in the program DCB.
Existing job control for these programs must be altered to request
a tape unit with the new recording characteristics and, if desired,
to change existing DCB parameters such as block size, number of
buffers, etc.
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IBM System/370 Specifications

General

Brand	IBM
Model	System/370
Category	Server
Language	English