pack

pack Consolidate workspace memory.
pack performs memory garbage collection. Extended MATLAB sessions may cause memory to become fragmented, preventing
large variables from being stored. pack is a command that saves all variables on disk, clears the memory, and then
reloads the variables.

If you run out of memory often, here are some additional system
specific tips:
Windows: Increase virtual memory using the control panel.
Unix: Ask your system manager to increase your Swap Space.

You should cd to a directory where you have “write” permission to execute this command successfully. The following lines of code will help you accomplish the consolidation of workspace memory.

cwd = pwd;
cd(tempdir);
pack
cd(cwd)

See also memory.