IBM AS/400 manual File Locking

Compile Time:

Override File

QTAPE to

File FMT1

RPG program

File name = QTAPE Format = E Device = SEQ

File Locking

FMT1

Execution Time:

No Override

QTAPE

File type =

DEVICE

Device type =

TAPE

Figure 137. Redirecting File Input and Output Example

File Locking

The OS/400 system allows a lock state (exclusive,

exclusive

allow

read,

update,

shared

no

update,

or

shared

for

read)

to

be

placed

on

a

the

execution

of

a

job.

Programs

within a

job

are

not

affected

b

file

lock

state

applies

only when

a

program

in

another job

tries

to

currently. The

file

lock

state

can

be

allocated

with

the

CL

command

cate

Object).

For

more

information

on

allocating

resources

and

lock

sta

Data

Management manual.

The OS/400 system places the following lock states on database files opens the files:

File Type	Lock State
Input	Shared	for	read
Update	Shared	for	update
Add	Shared	for	update
Output	Shared	for	update

The

shared-for-read lock state allows another

user to open the file

of

shared

for

read, shared

for

update, shared no update,

or

exc

but

the user cannot specify the exclusive

use of the file. The s

state

allows

another

user

to

open

the

file

with

shared-for-read

or

lock

state.

The

RPG program places an exclusive-allow-read

lock state on device fi

Another

user

can

open

the

file with a

shared-for-read

lock

state.

The

lock state placed on the file by the

RPG

program

can

be

chang

the

Allocate

Object

command.

Chapter 15. General File Considerations275