Please HELP!!!!!!!!!

I am trying to increase the size of our recovery log to stop database
backups from triggering during critical times.  When I try to add the
volume I receive the following message:

ANS8000I Addition of object cannot be completed due to the following
error:
ANR2452E Maximum recovery log capacity exceeded.

Here is the current status of our recovery log:

Available space                 4688            MB
Assigned capacity               4624            MB
Maximum extension       64                      MB
Maximum reduction               1640            MB
Page size                               4096            MB
Total Pages assigned    1183232 bytes
Used Pages                      762750

Our server is a 2.1.9 MVS server.