I suggest you use the EXTEND LOG command, documented in the ADSM Admin
Reference. The syntax is:
>>-DSMSERV EXTEND LOG--volname--size---------------------------><
Parameters :
volname
     Specifies the name of a new, formatted volume available for use as the
recovery log extension. This parameter is required. Use
     the DSMFMT utility to format the new volume.
size
     Specifies the size, in megabytes, of the recovery log extension. This
parameter is required. The specified size should be a multiple
     of 4 and at least 1 MB less than the actual volume size of the volume
specified in the volname parameter. For example, if the
     volume specified in the volname parameter is 5MB, the entered value for
the size parameter is 4.

Regards, Giulio John Tarella

Notes:John Tarella/Italy/IBM@IBMIT
Email: tarella AT ibm DOT net
Home page:  http://supporti.italy.ibm.com/home/tarella/tar.htm
ADSM home:  http://supporti.italy.ibm.com:8080/SUPPADSM.NSF?OpenDatabase
ADSM Consultant - IBM PSS - Stresa