Allocating an ACDS

The following access method services job allocates a 6-track ACDS.

  //STEP  EXEC PGM=IDCAMS
  //SYSUDUMP DD SYSOUT=*
  //SYSPRINT DD SYSOUT=*
  //SYSIN    DD *
    DEFINE CLUSTER(NAME(SMS.ACDS1.ACDS) LINEAR VOL(SMSV02) -
    TRK(6 6) SHAREOPTIONS(3,3)) -
    DATA(NAME(SMS.ACDS1.ACDS.DATA))
  /*

This job creates a VSAM linear data set named SMS.ACDS1.ACDS.

An ACDS must reside on a shared volume, accessible from all systems in the SMS complex. To ease recovery in case of failure, the ACDS should reside on a different volume than the COMMDS. Also, you should allocate a spare ACDS on a different shared volume. z/OS DFSMSdfp Storage Administration provides more information about the backup and recovery of control data sets.

You create the contents of an ACDS by activating a valid SCDS. The distinction between a valid SCDS and one that is not valid is described in z/OS DFSMSdfp Storage Administration. The control data set (ACDS or COMMDS) must reside on a volume that is not reserved by other systems for a long period of time because the control data set (ACDS or COMMDS) must be available to access for SMS processing to continue.

You should specify the REUSE option when you define an ACDS to avoid running into space problems (SMS reason code 6068) as result of subsequent ACDS updates, or IMPORT/EXPORT functions.