G'day Yary,

"I have this memory of Perl limiting how deep subroutine recursion could go, ..."

Perl only warns when a certain recursion depth is reached; it doesn't prevent you from recursing deeper.

"... but the following test suggests not:"

If you ask for warnings, you get them:

$ perl -E 'sub f{say $_[0] unless $_[0] % 10000;exit if $_[0] > 30000;
+f($_[0]+1)};f(1)'
10000
20000
30000

$ perl -wE 'sub f{say $_[0] unless $_[0] % 10000;exit if $_[0] > 30000
+;f($_[0]+1)};f(1)'
Deep recursion on subroutine "main::f" at -e line 1.
10000
20000
30000
[download]

"Just curious if there was a recursion limit, ..."

The limit is 100, i.e. on the 100th recursion, a warning is emitted.

$ perl -wE 'sub f{say $_[0] unless $_[0] % 33;exit if $_[0] >= 99;f($_
+[0]+1)};f(1)'
33
66
99
ken@ganymede: ~/tmp
$ perl -wE 'sub f{say $_[0] unless $_[0] % 33;exit if $_[0] >= 100;f($
+_[0]+1)};f(1)'
33
66
99
Deep recursion on subroutine "main::f" at -e line 1.
[download]

Search for "Deep recursion on subroutine" in perldiag for more details and additional information.

Also, if you're using the warnings pragma, which I strongly recommend, you can selectively turn off warning messages.