April 27, 1981
244.2 IBMVM/370 User's Guide
244.2 IBM
Page of GC20-1819-2 As Updated April 27, 1981 by TNL SN25-0828 For 5748-XE1 The fileid must be specified either in the FSCB for a file or
FSREAD,FSWRITE, FSOPEN, or FSERASE macro instruction you use
references the file.
on the
thatFSCBITNO: For an FSCB without the FORM=E option, the record or item
number-indicates the relative record number of the next record to be
read or written; it can be changed with theRECNO option. The default
value for this field is o.When you are reading files, a 0 indicates
that records are to be read sequentially, beginning with the first
record in the file. When you are writing files, a0 indicates that
records are to be written sequentially, beginning at the first record
following the end of the file, if the file already exists, or with
record 1, if it is a new file.
For anFSCB generated with the
contains the record or item number.FORM=E option, the FSCBAITN field
TheFSCBITNO field is reserved.
Whenever you read discontiguous files inCMS (that is, files with
missing records), the input buffer will be filled with the appropriate
number of bytes. Be aware that the flag byte in theFSCB may not
reflect whether the input buffer contains generated data items from
RDBUF.FSCBBQff: The buffer address, specified in the BUFFER option, indicates
the label of the buffer from which the record is to be written or into
which the record is to be read.You should always supply a buffer large
enough to accommodate the longest record you expect to read or write.
This field must be specified, either in theFSCB, or on the FSREAD or FSWRITE macro instruction. FSCBSIZE: This field indicates the number or nytes written-with each read or write operation. The default value is O. If
the buffer that you use represents the full length of the records you
are going to be reading or writing, you can use theBSIZE option to set
this field equal to your buffer length; when you are writing
variable-length records, use theBSIZE operand to indicate the length of
each record you write. This field must be specified.FSCB1Y: This field indicates the record format (RECFM) of the file. The
default value is F (fixed).
FSCBFLG: Theflag byte is X'20' indicating an extended FSCB generated when-the FOBM=E option is coded on the FSCB macro instruction. FSCBNQ!T: For an FSCB without the FORM=E option, this field contains the
number of whole records that are to be read or written in each read or
write operation. For fixed-length records, you can use theNOREC option
with theBSIZE option to block and deblock records. For variable-length
records, theNOREC parameter must be 1. The default for the FSCBNOIT field is 1.
For anFSCB generated with the FORM=E option, the FSCBANIT
contains the number of whole records to be read or written.FSCBNOIT field is reserved.
field
The
bytes that were actually read, so that if you are reading a
variable-length file, you can determine the size of the last record
read. TheFSREAD macro instruction places the information from this
field into register o.
FSCBAITN: The alternate record or item number indicates the relativerecord-number of the next record to be read or written in an extended FSCB format. See the description of the FSCBITNO field for the usage of
this field.
section 13. programming for theCMS Environment 245
FSREAD,
references the file.
on the
that
number-indicates the relative record number of the next record to be
read or written; it can be changed with the
value for this field is o.
that records are to be read sequentially, beginning with the first
record in the file. When you are writing files, a
records are to be written sequentially, beginning at the first record
following the end of the file, if the file already exists, or with
record 1, if it is a new file.
For an
contains the record or item number.
The
Whenever you read discontiguous files in
missing records), the input buffer will be filled with the appropriate
number of bytes. Be aware that the flag byte in the
reflect whether the input buffer contains generated data items from
RDBUF.
the label of the buffer from which the record is to be written or into
which the record is to be read.
enough to accommodate the longest record you expect to read or write.
This field must be specified, either in the
the buffer that you use represents the full length of the records you
are going to be reading or writing, you can use the
this field equal to your buffer length; when you are writing
variable-length records, use the
each record you write. This field must be specified.
default value is F (fixed).
FSCBFLG: The
number of whole records that are to be read or written in each read or
write operation. For fixed-length records, you can use the
with the
records, the
For an
contains the number of whole records to be read or written.
field
The
bytes that were actually read, so that if you are reading a
variable-length file, you can determine the size of the last record
read. The
field into register o.
FSCBAITN: The alternate record or item number indicates the relative
this field.
section 13. programming for the
