Record Insert Mode Characteristics - IBM 3741 Data Station Reference Manual

If you want to insert five records on track 01 beginning
with sector 05, the 3741 would put five deleted records
in sectors 05 through 09.
To create space in the data set, the 3741 moves the records
from the current record address through the last record in
the data set. The 3741 moves these records as many sectors
as the number of records to be inserted (up to 99). An
example of creating space for five records:
Current
Last Record
in Data Set
BOE
01001
Record Address
01005
10020 1
0025~Last
record
[ --------4.~~
after move
I
in data set
L...-----+---l --------'
101005
0\0\
010091
0\ 0 \ 0 \
Space filled with
deleted records.
When using the record insert function, there must be enough
space between EOO and EOE specified in the data set
label. That is, if you want to insert 50 records, but only
have 40 sectors available, (from E00 to EOE) in the data
set, an error occurs.
If all of the space created is not used, the remaining
deleted records will be ignored when processing data. If you
have deleted records, you must reset the deleted record (6)
error which the 3741 displays with each deleted record.
Therefore, if enough space was not specified for the number
of records to be inserted, you will realize it when you do
not get the deleted record (6) error. Search on content can
be used to search for the
0\
when records will be inserted
at some other time.
Record Insert Mode Characteristics
Enter Mode
No records are moved in this mode but it allows you to
create a space within your data set for records you might
want to add later. Deleted records are added starting at
the current disk address for the number of records
specified.
Update Mode
The machine searches to the last record in the data set.
Then it reads records in groups starting at this address· and
rewrites these records at their new addresses. After moving
all the records, the 3741 adds deleted records at the speci·
fied disk address for the number of records specified.
Verify Mode
The Record Insert mode cannot be selected while the 3741
is in the Verify mode. The 3741 must be placed in Update
mode before the Record Insert mode is selected.
Read Index Mode
The 3741 moves all records in the data set as if in Update
mode. Then the machine adds deleted records at the BOE
address.
Search Mode
The action taken by the machine depends on the mode it
was in prior to selecting Search mode. See one of the
above.
When all the records have been moved and the space filled
with deleted records, the 3741 returns to the disk address
of the first record of the space created.
The machine goes to update mode regardless of the mode
you were in previously. The machine also displays a
deleted record (6) error, goes to program 0, and blanks the
hold buffer.
Operation Modes and Considerations 21