OTMA ACEE flood control

The OTMA accessor environment element (ACEE) flood control function prevents virtual storage in the IMS control region from running out.

When OTMA security is enabled, for performance purposes OTMA caches in memory RACF® user profiles as a RACF accessor environment element (ACEE). The ACEE is then used in subsequent calls to RACF to determine the user ID's authorization to the IMS command or IMS transaction requested in the input message. Using the ACEE reduces I/O to RACF. When you enable OTMA ACEE flood control, you limit the number of RACF user profiles that can cache ACEEs, which in turn limits the number of ACEEs that are cached by OTMA.

To check whether the OTMA ACEE flood control function is enabled and to check the total number of OTMA ACEEs that are cached, issue the /DISPLAY OTMA command.

Procedure

  1. To enable OTMA ACEE flood control, in the DFSOTMA descriptor of the DFSYDTx member of the IMS PROCLIB data set, specify TOACEE=YES.
  2. To define the maximum number of RACF user IDs that can have cached ACEEs, specify a value for the ACEEUSR= parameter of the DFSOTMA descriptor.