At times when applying maintenance the special instructions state: IPL with CLPA required. What does that mean?
LPA means Link Pack Area and the C means create, create link pack area. You can specify CLPA as the default at IPL time.
If it is not your site's default then you can reply to the first IPL message at startup with: R 00,SYSP=xx,CLPA.
Where xx targets the SYS1.PARMLIB(IEASYSxx) member you want to start with.
You can specify it in that member to make it your default at IPL time.
See IBM documentation Initialization and Tuning Reference.