- Indicates that the DD statement describes a VSAM data set. Code
AMORG when data set access is through an ISAM interface program and
the DD statement contains VOLUME and UNIT parameters.
It is unnecessary
to code AMP=AMORG for a data set that is SMS-managed. An SMS data
set is cataloged at allocation; all information pertaining to the
data set creation (such as RECORG) must be fully defined at allocation
to ensure the success of the job.
- Specifies the number of I/O buffers that VSAM is to use for data
records. The minimum is 1 plus the STRNO subparameter number. This
value overrides the BUFND value specified in the ACB or GENCB macro,
or provides a value if one is not specified. If you omit STRNO, BUFND
must be at least 2.
If you omit BUFND from AMP and from the ACB
macro instruction, the system uses the STRNO number plus 1.
- Specifies the number of I/O buffers that VSAM is to use for index
records. This value overrides the BUFNI value specified in the ACB
or GENCB macro, or provides a value if one is not specified. If you
omit BUFNI from AMP and from the ACB macro instruction, VSAM uses
as many index buffers as the STRNO subparameter number; if you omit
both BUFNI and STRNO, VSAM uses 1 index buffer.
If data access
is through the ISAM interface program, specify for the BUFNI number
1 more than the STRNO number, or specify 2 if you omit STRNO, to simulate
having the highest level of an ISAM index resident. Specify a BUFNI
number 2 or more greater than the STRNO number to simulate having
intermediate levels of the index resident.
- Specifies the maximum number of bytes for the data and index buffers
in the user area. This value overrides the BUFSP value specified in
the ACB or GENCB macro, or provides a value if one is not specified.
If BUFSP specifies fewer bytes than the BUFFERSPACE parameter of
the access method services DEFINE command, the BUFFERSPACE number
overrides the BUFSP number.
- Requests a checkpoint/restart option. For more information, see z/OS DFSMSdfp Checkpoint/Restart.
- Requests no data set post-checkpoint modification tests.
- Requests neither a data-erase test nor data set post-checkpoint
- Requests no data-erase test.
- Requests a data-erase test and data set post-checkpoint modification
tests. If the CROPS subparameter is omitted, RCK is the default.
If you request an inappropriate option, such
as the data-erase test for an input data set, the system ignores the
- Specifies if VSAM batch logging will be performed for your VSAM
- Disables the VSAM batch logging function for your VSAM data set.
Changes made by applications will not be written to the MVS™ log
stream indicated on the LOGSTREAMID parameter.
- Enables the VSAM batch logging function for you VSAM data set.
Changes made by applications will be written to the MVS log
stream indicated on the LOGSTREAMID parameter.
- If FRLOG=REDO is specified, the LOGSTREAMID parameter must be
specified for the VSAM data set(s). If LOGSTREAMID is not specified,
IEC161I is issued.
- There is no default JCL value for FRLOG. If FRLOG is omitted,
the catalog value will be used.
- Indicates how the ISAM interface program is to process records
that the step’s processing program flags for deletion.
- Requests, when the data control block (DCB) contains OPTCD=L,
that the ISAM interface program is not to write into the data set
records marked for deletion by the processing program.
is specified without OPTCD=L in the DCB, the system ignores deletion
flags on records.
- Requests that the ISAM interface program is to keep in the data
set records marked for deletion by the processing program.
marked for deletion are to be kept but OPTCD=L is not in the DCB,
AMP=('OPTCD=L') is required.
Note: This parameter has the same
meaning and restrictions for the ISAM interface as it has for ISAM.
While it was not required in the ISAM job control language, you should
code it in the AMP parameter.
- Requests that the ISAM interface program is not to write into
the data set records marked for deletion by the processing program.
If the processing program had read the record for update, the ISAM
interface program deletes the record from the data set.
has the same effect as AMP=('OPTCD=I') coded with OPTCD=L in the DCB.
- For data sets with SMS, see the DD RECFM parameter described in .
ISAM record format used by the processing program. You must code this
RECFM subparameter when the record format is not specified in the
Note: This parameter has the same meaning and restrictions
for the ISAM interface as it has for ISAM. While it was not required
in the ISAM job control language, you should code it in the AMP parameter.
All VSAM requests are for unblocked records. If the processing
program requests blocked records, the ISAM interface program sets
the overflow-record indicator for each record to indicate that each
is being passed to the program unblocked.
- Indicates fixed-length records.
- Indicates blocked fixed-length records.
- Indicates variable-length records. If no RECFM is specified in
the AMP parameter or in the DCB, V is the default.
- Indicates blocked variable-length records.
- Indicates the number of request parameter lists the processing
program uses concurrently. The number must at least equal the number
of BISAM and QISAM requests that the program can issue concurrently.
If the program creates subtasks, add together the number of requests
for each subtask plus 1 for each subtask that sequentially processes
the data set. This value overrides the STRNO value specified in the
ACB or GENCB macro, or provides a value if one is not specified.
- Names a SYNAD exit routine. The ISAM interface program is to
load and exit to this routine if a physical or logical error occurs
when the processing program is gaining access to the data set.
The SYNAD parameter overrides a SYNAD exit routine specified in the
EXLST or GENCB macro instruction that generates the exit list. The
address of the intended exit list is specified in the access method
control block that links this DD statement to the processing program.
If no SYNAD exit is specified, the system ignores the AMP SYNAD parameter.
- Indicates that the generalized trace facility (GTF) executes with
your job to gather information about the opening, closing, and end-of-volume
processing for the data set defined on this DD statement. You can
use the interactive problem control system to print the trace output;
see z/OS MVS IPCS User's Guide.
subparameters are: HOOK, ECODE, KEY, PARM1, and PARM2. See z/OS DFSMS Using Data Sets for full information on the TRACE subparameter and the VSAM trace
facility, which you use to obtain diagnostic information during VSAM
- Specify one of these six values to override record access bias
in the data class in order to use System-Managed Buffering (SMB) without
changing the data class. See z/OS DFSMS Using Data Setsz/OS DFSMS Using Data Sets for details on System-Managed Buffering.
- Obtain buffers the same way the system would without SMB. This
is the default if you code no specification for the ACCBIAS subparameter.
- Force SMB and let the system determine the buffering technique
based on the ACB MACRF and storage class specification.
and SYSTEM are the only values you may use to specify record access
bias in the data class.
- SMB with direct optimization.
- SMB weighted for direct processing.
This option provides the
capability to use hiperspace.
- SMB with sequential optimization.
- SMB weighted for sequential processing.
- SMBDFR=Y or SMBDFR=N
- With direct optimization, use this subparameter to instruct VSAM
whether to defer writing of changed buffers to the medium until either
the data set is closed or the buffers are required for some other
request. See z/OS DFSMS Using Data Sets for further details on using SMBDFR.
- Specify a requirement for hiperspace where nn is an integer from
0 to 99. Use this parameter with direct optimization. The default
value is 0, which means that the system does not obtain any hiperspace.
- SMBVSP=nnK or SMBVSP=nnM
- Specify the amount of virtual buffer space to acquire for direct
optimized processing when opening the data set, where nn is 1 to 2048000
kilobytes or 1 to 2048 megabytes.
- When you specify MSG = SMBBIAS, the system issues message IEC161I
to indicate which access bias SMB has chosen. If
SYSTEM is specified in ACCBIAS or Record Access Bias, then the system
will choose an access bias for SMB, otherwise it will use what the
user specified in ACCBIAS. The possible values in the message are
DO, DW, SO, SW, CO, CR or ??, where ’??’ means OPEN could not determine
which one of the six bias values was used to create the initial control
block structure. The default is no message.
- Designate the residency for buffers and control blocks.
subparameter allows you to specify whether or not to allocate the
buffers and control blocks in 31-bit addressable storage. You can
use this field independently of SMB. With SMB the default location
is in 31-bit addressable storage ("above the 16-megabyte line").
Without SMB, the default is in 24-bit addressable storage ("below
The values you may specify for RMODE31 are:
- —Control blocks and buffers above the line.
- —Buffers (only) above the line.
- —Control blocks (only) above the line.
- —Control blocks and buffers below the line.
When you do not specify ACCBIAS, or when you
specify ACCBIAS=USER, if you specify nothing for RMODE31 in either
the JCL or the ACB, the system obtains the buffers and control blocks
in virtual storage with a 24-bit address.
if you specify nothing for RMODE31 in either the JCL or the ACB, the
system obtains the buffers in storage with an address greater than
16 million bytes.
When you specify CB or NONE for RMODE31, the
system obtains the buffers in 24-bit addressable storage.
you specify BUFF or NONE for RMODE31, the system obtains the control
blocks in 24-bit addressable storage.
program runs in 24-bit mode and you use locate mode processing for
the VSAM data set, you must obtain the buffers and control blocks
in 24-bit addressable storage.
Note: If your program runs with
local or global shared resources (LSR/GSR) and uses journaling (JRNAD)
or user processing (UPAD) exit routines, the exits must run in 31-bit
mode if you obtained the control blocks above the line.
capability to allocate above the line is necessary when either or
both of the following conditions exists:
- The number of data sets open to a job is quite large.
- The number of buffers is such as to cause a storage shortage if
kept in 24-bit addressable storage.
You may specify RMODE31 only with the JCL DD AMP parameter
or in the ACB. The RMODE31 subparameter of AMP overrides any RMODE31
values specified in the ACB.
The RMODE31 subparameter is available
for all data set types.