What is an equivalent of EDM in Linux?

Probably the Package Cache (PCKCACHESZ) is the closest thing, which is defined in the db cfg.

Is it in DBM1?

Package cache is in the db shared memory which is kind of similar to DBM1. Marcus_A will correct me. This db shared memory set also includes bufferpools, memory for utilities, locks (IRLM), sorts ...

Although similar at the SQL level, DB2 for z/OS and DB2 for Linux/UNIX/Windows are two completely separate products. At the physical level they are completely different different.

Since the EDM Pool contains cached packages and plans, and also skeleton cursor table, I suggested that the Package Cache in DB2 for Linux/UNIX/Windows provided a similar function, but there is no one-to-one correspondence since the two databases products are very different below the SQL level.

Do I need to restart a subsystem after making EDM changes?

Are you asking about DB2 on z/OS or DB2 on Linux? If Linux, there are no subsystems. We have instances which is kind of similar to subsystems. Package cache is a database configuration parameter (kind of similar to subsystem zparms) and the change to the package cache is dynamic.