ABCs of z/OS System Programming Volume 3 - IBM Redbooks

2.11 IGDSMSxx parmlib member support
Defining format large data set in parmlib (z/OS V1R9)
BLOCKTOKENSIZE(REQUIRE | NOREQUIRE)
Figure 2-11 Using large format data sets
Using BLOCKTOKENSIZE(REQUIRE)
If your installation uses the default BLOCKTOKENSIZE(REQUIRE) setting in PARMLIB
member IGDSMSxx, you can issue the following command to see the current
BLOCKTOKENSIZE settings, from the MVS console:
D SMS,OPTIONS
REQUIRE: - Requires every open for a large format data
set to use BLOCKTOKENSIZE=LARGE on the DCBE
macro
NOREQUIRE: - Allows applications to access large
format data sets under more conditions without having to
specify BLOCKTOKENSIZE=LARGE on DCBE macro
Services updated for large format data sets
Large format data sets with BLOCKTOKENSIZE(REQUIRE)
The following services are updated for large format data sets:
ALLOCATE For a new or existing large format data set, use the
DSNTYPE(LARGE) keyword.
REXX EXECIO Using EXECIO DISKR to read a LARGE format SEQ data set will
work as long as the data set is 64 K trks, expect an ABEND213-17. Using EXECIO DISKW to
attempt to write to any LARGE format data set will fail with
ABEND213-15.
CLIST support Using CLIST OPENFILE INPUT/GETFILE and OPENFILE
OUTPUT/PUTFILE, as follows:
Using CLIST OPENFILE INPUT/GETFILE to read a LARGE format
SEQ data set will work as long as the data set is