How to use available memory for data cache?

I have ASE with following memory situation when running sp_configure memory:

additional network memory

0 0 0 0 bytes dynamic allocate max shared memory 0 0 1 1 switch dynamic compression memory size 0 152 0 0 memory pages(2k) dynamic engine memory log size 0 2 0 0 memory pages(2k) dynamic heap memory per user 4096 0 4096 4096 bytes dynamic lock shared memory 0 0 0 0 switch static max memory 45056 10240000 5120000 5120000 memory pages(2k) dynamic memory alignment boundary 2048 0 2048 2048 bytes static memory per worker process 1024 66 4096 4096 bytes dynamic messaging memory 400 0 400 400 memory pages(2k) dynamic shared memory starting address 0 0 0 0 not applicable static total logical memory 32768 9227998 4612856 4613999 memory pages(2k) read-only total physical memory 0 10240000 0 5120000 memory pages(2k) read-only An additional 1012002 K bytes of memory is available for reconfiguration. This is the difference between 'max memory' and 'total logical memory'.

with it said there are 1012002 K = 988.28M memory available for reconfiguration. Then I try to create a new data cache with 900M, but I get following error:

Number (10879) Severity (16) State (1) Server (MyServer) Procedure (sp_cacheconfig) The current 'max memory' value '5120000', is not sufficient to change the size of cache 'my new cache' to '900.000M' (921600 KB). 'max memory' should be greater than 'total logical memory' '5122771' required for the configuration.

How to resolve this issue?