IBM OS/390 User Manual
15.4.1.10 NOTAPEMK NOLABEL
These are specified in the JCL in the LABEL parameter of the DD statement.
15.4.2 Supported but to be Avoided
In OS most of the environment parameters can be specified in the DCB. At
OPEN, MVS merges the information from the program, from the label if the file
exists already, and from the DCB parameters in the DD statement. It is therefore
damaging to specify the physical blocksize in the program, because a
re-compilation is involved if the blocking factor is to be changed. The following
options should therefore be omitted:
OPEN, MVS merges the information from the program, from the label if the file
exists already, and from the DCB parameters in the DD statement. It is therefore
damaging to specify the physical blocksize in the program, because a
re-compilation is involved if the blocking factor is to be changed. The following
options should therefore be omitted:
BLKSIZE
KEYLENGTH
KEYLOC
KEYLENGTH
KEYLOC
15.4.3 The
″
TOTAL
″
Option
A new option can be specified: TOTAL. This option, which is effective only with
CONSECUTIVE files, allows PL/I to branch directly to MVS access method
routines without using the TRANSIENT library modules; there is therefore a
performance improvement. This requires that the file be declared as completely
as possible. Only the blocking factor may be specified in the DD statement, and
no options may be specified at OPEN. Users must weigh the benefits of improved
performance (via the TOTAL option) against the advantages of complete MVS
DCB merge.
CONSECUTIVE files, allows PL/I to branch directly to MVS access method
routines without using the TRANSIENT library modules; there is therefore a
performance improvement. This requires that the file be declared as completely
as possible. Only the blocking factor may be specified in the DD statement, and
no options may be specified at OPEN. Users must weigh the benefits of improved
performance (via the TOTAL option) against the advantages of complete MVS
DCB merge.
15.4.4 The SIS Option (Sequential Insert Strategy)
This option applies to (and only to) processing of a VSAM KSDS using a PL/I file
with the DIRECT attribute. It causes VSAM to insert new records using SIS
(Sequential Insert Strategy) rather than direct insert strategy. All other
environment options, in the case of VSAM files, are identical in MVS PL/I and
DOS PL/I.
with the DIRECT attribute. It causes VSAM to insert new records using SIS
(Sequential Insert Strategy) rather than direct insert strategy. All other
environment options, in the case of VSAM files, are identical in MVS PL/I and
DOS PL/I.
15.5 Calling SORT from PL/I
15.5.1 Interfaces Offered
The DOS PL/I Optimizer provides, through PLISRTx, an interface to DOS/VS
SORT/MERGE Version 2 (5746-SM2) and other VSE supported sorts.
SORT/MERGE Version 2 (5746-SM2) and other VSE supported sorts.
The MVS PL/I Optimizer offers, through an interface of the same name, access to
DFSORT (5740-SM1).
DFSORT (5740-SM1).
The four sort entry points offered by PL/I are the same in MVS and VSE:
PLISRTA, PLISRTB, PLISRTC and PLISRTD. The only exits supported by PL/I are
E15 and E35.
PLISRTA, PLISRTB, PLISRTC and PLISRTD. The only exits supported by PL/I are
E15 and E35.
15.5.2 Parameters to be Passed
The parameters for calling sort are fortunately the same. The number of these
parameters depends on the entry point used. Let us take the most general case
(PLISRTD) which invokes exits E15 and E35. The parameters to be passed are
described in the following sections.
parameters depends on the entry point used. Let us take the most general case
(PLISRTD) which invokes exits E15 and E35. The parameters to be passed are
described in the following sections.
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