You want to change the CAIMST00 member name for CAMASTER by another one, for example: CAIMSTL0.
Is this allowable?
No, you cannot use another name for the CAIMST00 member, e.g. CAIMSTL0.
You can only change the name of the CAIMST20 member if desired.
As found in the CA Common Services r14.1 Reference Guide:
CAIMST20 Logical Parmlib Member Name
The Logical Parmlib member name, CAIMST20, can be overridden to specify another valid name.
To override the CAIMST20 member name, add a keyword on the CAMSINIT control statement ASMMEM,
specifying the override member name:
ASMMEM(CAIMST10) /*Override CAIMST20 member name*/