Multiple access to libraries occurs when several users access the same library at the same time, either in read or in write mode. Access can take place from different tasks. The tasks can run under different user IDs.
Unrestricted multiple access to libraries is possible under the following conditions:
the necessary access rights have been granted
access is not via Remote File Access (RFA).
for libraries on shared pubsets:
the accessing tasks are running on different systems, that form an XCS network.
The user can explicitly restrict the use of multiple access with the following commands:
/ADD-FILE-LINK ...,SUPPORT=*DISK(SHARED-UPDATE=*NO)
Libraries are opened by default with SHARED-UPDATE=*YES.
/ADD-FILE-LINK SHARED-UPDATE=*NO and the opening of this library with the specified link name prevents further update accesses.
/SECURE-RESOURCE-ALLOCATION FILE=
The library is reserved exclusively for this task.
/MODIFY-FILE-ATTRIBUTES ...,PROTECTION=
Only users who have the necessary access rights can access the library.
For a description of these commands, see the “Commands” manual [1 (Related publications)].