LOCK ENTRY SIZE field

The value of the LOCK ENTRY SIZE field specifies the initial size, in bytes, of individual lock entries in the lock table portion of the lock structure.

Acceptable values: 2, 4, 8
Default: 2
Update: edit IRLM start procedure
DSNZPxxx: none
Recommendation: If you have seven or fewer members in your data sharing group, use the default value for the most efficient use of coupling lock structure space. If you have more than seven members, use a value of 4 to avoid an automatic rebuild for maximum connections.

Db2 assigns a value to the MAXUSRS parameter in the irlmproc procedure based on the LOCK ENTRY SIZE value. The following table shows the LOCK ENTRY SIZE values and the corresponding assigned MAXUSRS values.

Table 1. Lock entry sizes and corresponding MAXUSRS values
LOCK ENTRY SIZE MAXUSRS value
2 7
4 23
8 32
Important: Start of changeThe lock entry size and the lock entry table (LTE) width do not change when the number of lock table entries changes.
The LTE width increases when you perform these steps:
  1. Perform the following steps on each member of the data sharing group:
    1. Increase the MAXUSRS value to a value in a higher MAXUSRS range.
      The MAXUSRS value ranges are:
      • 7 or less
      • ≥ 8 and < 24
      • ≥ 24 and < 33

      For example, if MAXUSRS is changed from 7 to 8, the value is in a higher MAXUSRS range.

    2. Restart the data sharing group member.

    You can perform the steps above on all members at the same time, or serially, over a period of time.

  2. Rebuild the lock structure for the data sharing group.
When MAXUSRS is changed to a value in a lower MAXUSRS range (for example, from 8 to 7), the LTE width does not change as long as the lock structure remains allocated. To reduce the LTE width, you need to perform these steps:
  1. Shut down the data sharing group.
  2. Deallocate the lock structure by issuing the z/OS® SETXCF FORCE command. For more information, see Deallocating structures by force.
  3. Restart the data sharing group.
End of change