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Purpose Use this macroinstruction to allow
an application to change the pageable state of a buffer.
Usage An application can use this macroinstruction
to make the buffer guaranteed to be pageable or eligible to be paged.
When
BUFTYPE=PAGEELIG is specified on this macroinstruction, the buffer
is marked as eligible to be paged. The buffer is not physically unfixed
unless CSM requires real storage to satisfy another CSM request.
This avoids the potential overhead of unnecessary fixing and freeing
of storage.
This macroinstruction can be used to avoid consuming
real storage for data that is being held in a buffer for possible
use at a later time.
When BUFTYPE=PAGEABLE is specified on
this macroinstruction, the buffer is marked as guaranteed to be pageable.
This macroinstruction be used when a system service requires pageable
storage on input. This macroinstruction can be issued for a buffer
consisting of only one image. This restriction guarantees that a user
of a buffer that has multiple images can successfully issue a FIX_BUFFER
request if necessary. Fixing a buffer requires that the entire buffer
be fixed, even if the user is interested in only a piece of the buffer.
Syntax
main diagram
>>-+------+--IVTCSM REQUEST--=--PAGE_BUFFER--| parameters-1 |--->
'-name-'
>--+------------------------+--+------------------------+------->
'-,--RETCODE--=--retcode-' '-,--RSNCODE--=--rsncode-'
.-,--PLISTVER--=--IMPLIED_VERSION-.
>--+---------------------------------+-------------------------->
+-,--PLISTVER--=--MAX-------------+
'-,--PLISTVER--=--0---------------'
.-,--MF--=--S--------------------------------------.
>--+--------------------------------------------------+--------><
| .-,--0D---. |
+-,--MF--=--(--L--,--list addr--+---------+--)-----+
| '-,--attr-' |
| .-,--COMPLETE-. |
+-,--MF--=--(--E--,--list addr--+-------------+--)-+
| '-,--NOCHECK--' |
| .-,--COMPLETE-. |
'-,--MF--=--(--M--,--list addr--+-------------+--)-'
'-,--NOCHECK--'
parameters-1
>>-,--BUFLIST--=--buflist--,--BUFNUM--=--bufnum----------------->
>--+-,--BUFTYPE--=--PAGEELIG-+--+----------------+-------------->
'-,--BUFTYPE--=--PAGEABLE-' '-,--GAP--=--gap-'
>--+--------------------------+--+----------------------+------->
'-,--ERRBFLST--=--errbflst-' '-,--THREAD--=--thread-'
>--+------------------------+----------------------------------><
'-,--UTILRTN--=--utilrtn-'
Parameters - name
- An optional symbol, starting in column 1, that is the name on
the IVTCSM macro invocation. The name must conform to the rules for
an ordinary assembler language symbol.
- ,BUFLIST=buflist
- A required input parameter of an area containing a list of buffer
entries. The number of entries in the list is specified by BUFNUM.
An entry in the buffer list is mapped by IVTBUFL.
The following
fields in IVTBUFL are required as input for this request:
The following field in IVTBUFL is returned as output by CSM
for this request:
To code, specify the RS-type address, or address in
register (2)-(12), of a field.
- ,BUFNUM=bufnum
- A required input parameter, specifying the number of buffers to
be made pageable or eligible to be paged.
To code, specify the
RS-type address, or address in register (2)-(12), of a fullword field.
- ,BUFTYPE=
- A required parameter, specifying whether the buffers are to be
guaranteed to be pageable or eligible to be made pageable.
- ,BUFTYPE=PAGEELIG
- Indicates that the buffers are eligible to be made pageable.
- ,BUFTYPE=PAGEABLE
- Indicates that the buffers are to be guaranteed to be pageable.
- ,ERRBFLST=errbflst
- An optional output parameter containing the number of the last
buffer entry that was successfully processed when an error is detected
during processing of the macroinstruction.
To code, specify the
RS-type address, or address in register (2)-(12), of a fullword field.
- ,GAP=gap
- An optional input parameter, specifying the number of bytes used
to separate buffer entries. This parameter allows the buffer entries
to be in discontiguous storage. If GAP is not specified, buffer entries
are contiguous.
To code, specify the RS-type address, or address
in register (2)-(12), of a fullword field.
- ,MF=
- An optional input parameter that specifies the macro form.
- MF=S
- Specifies the standard form of the macro, which builds an inline
parameter list and generates the macro invocation to transfer control
to the service. MF=S is the default
- MF=L
- Specifies the list form of the macro. Use the list form together
with the execute form of the macro for applications that require reentrant
code. The list form defines an area of storage that the execute form
uses to store the parameters. Only the PLISTVER parameter be coded
with the list form of the macro.
- MF=E
- Specifies the execute form of the macro. Use the execute form
together with the list form of the macro for applications that require
reentrant code. The execute form of the macro stores the parameters
into the storage area defined by the list form, and generates the
macro invocation to transfer control to the service.
- MF=M
- Use this value together with the list and execute forms of the
macro for service routines that need to provide different options
according to user-provided input. Use the list form to define a storage
area; use the modify form to set the appropriate options; then use
the execute form to call the service.
- ,list addr
- The name of a storage area to contain the parameters. For MF=S,
MF=E, and MF=M, this can be an RS-type address or an address in register
(1)-(12).
- ,attr
- An optional input string 1 - 60 characters in length that you
use to force boundary alignment of the parameter list. Use a value
of 0F to force the parameter list to a word boundary, or 0D to force
the parameter list to a doubleword boundary. If you do not code attr,
the system provides a value of 0D.
- ,COMPLETE
- Specifies that the system is to check for required parameters
and supply defaults for omitted optional parameters.
- ,NOCHECK
- Specifies that the system is not to check for required parameters
and is not to supply defaults for omitted optional parameters.
Note: Use the modify and execute forms of IVTCSM
in the following order: - Use IVTCSM ...MF=(M,list-addr,COMPLETE) specifying appropriate
parameters, including all required ones.
- Use IVTCSM ...MF=(M,list-addr,NOCHECK), specifying the parameters
that you want to change.
- Use IVTCSM ...MF=(E,list-addr,NOCHECK), to execute the macro.
- ,PLISTVER=
- An optional input parameter that specifies the version of the
macro. PLISTVER determines which parameter list the system generates.
PLISTVER is an optional input parameter on all forms of the macro,
including the list form. When using PLISTVER, specify it on all macro
forms used for a request and with the same value on all of the macro
forms. The values are:
- IMPLIED_VERSION
- The lowest version that allows all parameters specified on the
request to be processed. If you omit the PLISTVER parameter, IMPLIED_VERSION
is the default.
- MAX
- Code this value if you want the parameter list to be the largest
size currently possible. This size might increase from release to
release and affect the amount of storage that your program needs.
If you can tolerate the size change, always specify PLISTVER=MAX
on the list form of the macro. Specifying MAX ensures that the list-form
parameter list is always long enough to hold all the parameters you
might specify on the execute form; in this way, MAX ensures that the
parameter list does not overwrite nearby storage.
- 0
- Code this value if you use the currently available parameters.
To code, specify one of the following values: - IMPLIED_VERSION
- MAX
- A decimal value of 0
- ,RETCODE=retcode
- An optional output parameter into which the return code is to
be copied from GPR 15.
To code, specify the RS-type address of
a fullword field, or register (2)-(12).
- ,RSNCODE=rsncode
- An optional output parameter into which the reason code is to
be copied from GPR 0.
To code, specify the RS-type address of
a fullword field, or register (2)-(12).
- ,THREAD=thread
- An optional input parameter, specifying a unique identifier that
is placed in the CSM trace entry to correlate trace records with the
application that is requesting the buffers. It is the CSM user's responsibility
to ensure that this value is different from the THREAD value specified
by other users of the CSM. One way this can be achieved is by specifying
an ECSA control block for THREAD.
To code, specify the RS-type
address, or address in register (2)-(12), of a 4-character field.
- ,UTILRTN=utilrtn
- An optional input parameter that is issued from a utility routine.
Specify the utility routine caller's address to be placed in the CSM
trace entry. If this parameter is omitted, only the address of the
CSM request issuer is placed in the CSM trace entry. This parameter
is relevant only to the tracing process. It should be specified only
if the CSM user requires identification of the caller of a utility
routine in the CSM trace entry.
To code, specify the RS-type address,
or address in register (2)-(12), of a fullword field.
Return codes The following codes can be
returned to the application on this macroinstruction: - Return code
- Meaning
- 0
- Request completed successfully.
- 4
- Request did not complete successfully. See the following reason
codes to determine the type of error encountered.
- Reason code
- Meaning
- 2
- Requested function not supported at the present time, service
has not been initialized.
- 7
- Pool token specified is not valid.
- 8
- Instance ID in the input pool token does not match that of the
buffer, possible attempt to use a buffer that has been freed.
- 10
- Request to make a buffer pageable denied, more than one image
of the buffer exists.
- 20
- BUFTYPE value specified is not valid for this request.
- 8
- System error while processing the request
- Reason code
- Meaning
- 1
- Unable to obtain storage for request.
- 6
- An abend occurred while processing this request.
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